diff --git a/docs/usage.md b/docs/usage.md
index 7f5c58b..12abff7 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -75,3 +75,73 @@ config = ProjectConfig(
 print(config)
 # ProjectConfig (config_path=/some/other/path/pyproject.toml)
 ```
+
+# Validation
+
+`maison` offers optional schema validation using [pydantic](https://pydantic-docs.helpmanual.io/).
+
+To validate a configuration, first create a schema which subclasses `ConfigSchema`:
+
+```python
+from maison import ConfigSchema
+
+class MySchema(ConfigSchema):
+  foo: str = "my_default"
+```
+
+!!! note ""
+    `ConfigSchema` offers all the same functionality as the `pydantic` [BaseModel](https://pydantic-docs.helpmanual.io/usage/models/)
+
+Then inject the schema when instantiating a `ProjectConfig`:
+
+```python
+from maison import ProjectConfig
+
+config = ProjectConfig(project_name="acme", schema=MySchema)
+```
+
+To validate the config, simply run `validate()` on the config instance:
+
+```python
+config.validate()
+```
+
+If the configuration is invalid, a `pydantic` `ValidationError` will be raised. If the
+configuration is valid, nothing will happen.
+
+## Casting and default values
+
+By default, `maison` will replace the values in the config with whatever comes back from
+the validation. For example, for a config file that looks like this:
+
+```toml
+[tool.acme]
+foo = 1
+```
+
+And a schema that looks like this:
+
+```python
+class MySchema(ConfigSchema):
+  foo: str
+  bar: str = "my_default"
+```
+
+Running the config through validation will render the following:
+
+```python
+config = ProjectConfig(project_name="acme", schema=MySchema)
+
+config.to_dict() # {"foo": 1}
+
+config.validate()
+config.to_dict() # {"foo": "1", "bar": "my_default"}
+```
+
+If you prefer to keep the config values untouched and just perform simple validation,
+add a `use_schema_values=False` argument to the `validate` method.
+
+## Schema precedence
+
+The `validate` method also accepts a `schema` is an argument. If one is provided here,
+it will be used instead of a schema passed as an init argument.
diff --git a/poetry.lock b/poetry.lock
index 7baf4c6..58c1e33 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,88 +1,86 @@
 [[package]]
-category = "dev"
-description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
 name = "appdirs"
+version = "1.4.4"
+description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.4.4"
 
 [[package]]
-category = "dev"
-description = "Utilities for refactoring imports in python-like syntax."
 name = "aspy.refactor-imports"
+version = "2.2.0"
+description = "Utilities for refactoring imports in python-like syntax."
+category = "dev"
 optional = false
 python-versions = ">=3.6.1"
-version = "2.2.0"
 
 [package.dependencies]
 cached-property = "*"
 
 [[package]]
-category = "dev"
-description = "Atomic file writes."
-marker = "sys_platform == \"win32\""
 name = "atomicwrites"
+version = "1.4.0"
+description = "Atomic file writes."
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "1.4.0"
 
 [[package]]
-category = "dev"
-description = "Classes Without Boilerplate"
 name = "attrs"
+version = "21.2.0"
+description = "Classes Without Boilerplate"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
-version = "21.2.0"
 
 [package.extras]
-dev = ["coverage (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface", "furo", "sphinx", "sphinx-notfound-page", "pre-commit"]
+dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface", "furo", "sphinx", "sphinx-notfound-page", "pre-commit"]
 docs = ["furo", "sphinx", "zope.interface", "sphinx-notfound-page"]
-tests = ["coverage (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface"]
-tests_no_zope = ["coverage (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins"]
+tests = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface"]
+tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins"]
 
 [[package]]
-category = "dev"
-description = "Compatibility shim providing selectable entry points for older implementations"
 name = "backports.entry-points-selectable"
+version = "1.1.0"
+description = "Compatibility shim providing selectable entry points for older implementations"
+category = "dev"
 optional = false
 python-versions = ">=2.7"
-version = "1.1.0"
 
 [package.dependencies]
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = "*"
+importlib-metadata = {version = "*", markers = "python_version < \"3.8\""}
 
 [package.extras]
 docs = ["sphinx", "jaraco.packaging (>=8.2)", "rst.linker (>=1.9)"]
 testing = ["pytest (>=4.6)", "pytest-flake8", "pytest-cov", "pytest-black (>=0.3.7)", "pytest-mypy", "pytest-checkdocs (>=2.4)", "pytest-enabler (>=1.0.1)"]
 
 [[package]]
-category = "dev"
-description = "Security oriented static analyser for python code."
 name = "bandit"
+version = "1.7.0"
+description = "Security oriented static analyser for python code."
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "1.7.0"
 
 [package.dependencies]
+colorama = {version = ">=0.3.9", markers = "platform_system == \"Windows\""}
 GitPython = ">=1.0.1"
 PyYAML = ">=5.3.1"
-colorama = ">=0.3.9"
 six = ">=1.10.0"
 stevedore = ">=1.20.0"
 
 [[package]]
-category = "dev"
-description = "The uncompromising code formatter."
 name = "black"
+version = "20.8b1"
+description = "The uncompromising code formatter."
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "20.8b1"
 
 [package.dependencies]
 appdirs = "*"
 click = ">=7.1.2"
+dataclasses = {version = ">=0.6", markers = "python_version < \"3.7\""}
 mypy-extensions = ">=0.4.3"
 pathspec = ">=0.6,<1"
 regex = ">=2020.1.8"
@@ -90,130 +88,118 @@ toml = ">=0.10.1"
 typed-ast = ">=1.4.0"
 typing-extensions = ">=3.7.4"
 
-[package.dependencies.dataclasses]
-python = "<3.7"
-version = ">=0.6"
-
 [package.extras]
 colorama = ["colorama (>=0.4.3)"]
 d = ["aiohttp (>=3.3.2)", "aiohttp-cors"]
 
 [[package]]
-category = "dev"
-description = "A decorator for caching properties in classes."
 name = "cached-property"
+version = "1.5.2"
+description = "A decorator for caching properties in classes."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.5.2"
 
 [[package]]
-category = "dev"
-description = "Python package for providing Mozilla's CA Bundle."
 name = "certifi"
+version = "2021.10.8"
+description = "Python package for providing Mozilla's CA Bundle."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "2021.10.8"
 
 [[package]]
-category = "dev"
-description = "Validate configuration and produce human readable error messages."
 name = "cfgv"
+version = "3.3.1"
+description = "Validate configuration and produce human readable error messages."
+category = "dev"
 optional = false
 python-versions = ">=3.6.1"
-version = "3.3.1"
 
 [[package]]
-category = "dev"
-description = "The Real First Universal Charset Detector. Open, modern and actively maintained alternative to Chardet."
-marker = "python_version >= \"3\""
 name = "charset-normalizer"
+version = "2.0.7"
+description = "The Real First Universal Charset Detector. Open, modern and actively maintained alternative to Chardet."
+category = "dev"
 optional = false
 python-versions = ">=3.5.0"
-version = "2.0.7"
 
 [package.extras]
 unicode_backport = ["unicodedata2"]
 
 [[package]]
-category = "main"
-description = "Composable command line interface toolkit"
 name = "click"
+version = "8.0.3"
+description = "Composable command line interface toolkit"
+category = "main"
 optional = false
 python-versions = ">=3.6"
-version = "8.0.3"
 
 [package.dependencies]
-colorama = "*"
-
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = "*"
+colorama = {version = "*", markers = "platform_system == \"Windows\""}
+importlib-metadata = {version = "*", markers = "python_version < \"3.8\""}
 
 [[package]]
-category = "main"
-description = "Cross-platform colored terminal text."
-marker = "platform_system == \"Windows\" or sys_platform == \"win32\" or platform_system == \"Windows\""
 name = "colorama"
+version = "0.4.4"
+description = "Cross-platform colored terminal text."
+category = "main"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
-version = "0.4.4"
 
 [[package]]
-category = "dev"
-description = "Code coverage measurement for Python"
 name = "coverage"
+version = "5.5"
+description = "Code coverage measurement for Python"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
-version = "5.5"
 
 [package.dependencies]
-[package.dependencies.toml]
-optional = true
-version = "*"
+toml = {version = "*", optional = true, markers = "extra == \"toml\""}
 
 [package.extras]
 toml = ["toml"]
 
 [[package]]
-category = "dev"
-description = "A utility for ensuring Google-style docstrings stay up to date with the source code."
 name = "darglint"
+version = "1.8.1"
+description = "A utility for ensuring Google-style docstrings stay up to date with the source code."
+category = "dev"
 optional = false
 python-versions = ">=3.6,<4.0"
-version = "1.8.1"
 
 [[package]]
-category = "dev"
-description = "A backport of the dataclasses module for Python 3.6"
-marker = "python_version < \"3.7\""
 name = "dataclasses"
+version = "0.6"
+description = "A backport of the dataclasses module for Python 3.6"
+category = "main"
 optional = false
 python-versions = "*"
-version = "0.6"
 
 [[package]]
-category = "dev"
-description = "Distribution utilities"
 name = "distlib"
+version = "0.3.3"
+description = "Distribution utilities"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "0.3.3"
 
 [[package]]
-category = "dev"
-description = "Docutils -- Python Documentation Utilities"
 name = "docutils"
+version = "0.17.1"
+description = "Docutils -- Python Documentation Utilities"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
-version = "0.17.1"
 
 [[package]]
-category = "dev"
-description = "A parser for Python dependency files"
 name = "dparse"
+version = "0.5.1"
+description = "A parser for Python dependency files"
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "0.5.1"
 
 [package.dependencies]
 packaging = "*"
@@ -224,41 +210,38 @@ toml = "*"
 pipenv = ["pipenv"]
 
 [[package]]
-category = "dev"
-description = "A platform independent file lock."
 name = "filelock"
+version = "3.3.1"
+description = "A platform independent file lock."
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "3.3.1"
 
 [package.extras]
 docs = ["furo (>=2021.8.17b43)", "sphinx (>=4.1)", "sphinx-autodoc-typehints (>=1.12)"]
 testing = ["covdefaults (>=1.2.0)", "coverage (>=4)", "pytest (>=4)", "pytest-cov", "pytest-timeout (>=1.4.2)"]
 
 [[package]]
-category = "dev"
-description = "the modular source code checker: pep8 pyflakes and co"
 name = "flake8"
+version = "3.9.2"
+description = "the modular source code checker: pep8 pyflakes and co"
+category = "dev"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,>=2.7"
-version = "3.9.2"
 
 [package.dependencies]
+importlib-metadata = {version = "*", markers = "python_version < \"3.8\""}
 mccabe = ">=0.6.0,<0.7.0"
 pycodestyle = ">=2.7.0,<2.8.0"
 pyflakes = ">=2.3.0,<2.4.0"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = "*"
-
 [[package]]
-category = "dev"
-description = "Automated security testing with bandit and flake8."
 name = "flake8-bandit"
+version = "2.1.2"
+description = "Automated security testing with bandit and flake8."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "2.1.2"
 
 [package.dependencies]
 bandit = "*"
@@ -267,12 +250,12 @@ flake8-polyfill = "*"
 pycodestyle = "*"
 
 [[package]]
-category = "dev"
-description = "A plugin for flake8 finding likely bugs and design problems in your program. Contains warnings that don't belong in pyflakes and pycodestyle."
 name = "flake8-bugbear"
+version = "21.9.2"
+description = "A plugin for flake8 finding likely bugs and design problems in your program. Contains warnings that don't belong in pyflakes and pycodestyle."
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "21.9.2"
 
 [package.dependencies]
 attrs = ">=19.2.0"
@@ -282,35 +265,35 @@ flake8 = ">=3.0.0"
 dev = ["coverage", "black", "hypothesis", "hypothesmith"]
 
 [[package]]
-category = "dev"
-description = "Extension for flake8 which uses pydocstyle to check docstrings"
 name = "flake8-docstrings"
+version = "1.6.0"
+description = "Extension for flake8 which uses pydocstyle to check docstrings"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.6.0"
 
 [package.dependencies]
 flake8 = ">=3"
 pydocstyle = ">=2.1"
 
 [[package]]
-category = "dev"
-description = "Polyfill package for Flake8 plugins"
 name = "flake8-polyfill"
+version = "1.0.2"
+description = "Polyfill package for Flake8 plugins"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.0.2"
 
 [package.dependencies]
 flake8 = "*"
 
 [[package]]
-category = "dev"
-description = "Python docstring reStructuredText (RST) validator"
 name = "flake8-rst-docstrings"
+version = "0.2.3"
+description = "Python docstring reStructuredText (RST) validator"
+category = "dev"
 optional = false
 python-versions = ">=3.3"
-version = "0.2.3"
 
 [package.dependencies]
 flake8 = ">=3.0.0"
@@ -318,270 +301,264 @@ pygments = "*"
 restructuredtext-lint = "*"
 
 [[package]]
-category = "dev"
-description = "Git Object Database"
 name = "gitdb"
+version = "4.0.9"
+description = "Git Object Database"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "4.0.9"
 
 [package.dependencies]
 smmap = ">=3.0.1,<6"
 
 [[package]]
-category = "dev"
-description = "Python Git Library"
 name = "gitpython"
+version = "3.1.20"
+description = "Python Git Library"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "3.1.20"
 
 [package.dependencies]
 gitdb = ">=4.0.1,<5"
-
-[package.dependencies.typing-extensions]
-python = "<3.10"
-version = ">=3.7.4.3"
+typing-extensions = {version = ">=3.7.4.3", markers = "python_version < \"3.10\""}
 
 [[package]]
-category = "dev"
-description = "File identification library for Python"
 name = "identify"
+version = "2.3.1"
+description = "File identification library for Python"
+category = "dev"
 optional = false
 python-versions = ">=3.6.1"
-version = "2.3.1"
 
 [package.extras]
 license = ["editdistance-s"]
 
 [[package]]
-category = "dev"
-description = "Internationalized Domain Names in Applications (IDNA)"
-marker = "python_version >= \"3\""
 name = "idna"
+version = "3.3"
+description = "Internationalized Domain Names in Applications (IDNA)"
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "3.3"
 
 [[package]]
-category = "main"
-description = "Read metadata from Python packages"
-marker = "python_version < \"3.8\""
 name = "importlib-metadata"
+version = "4.8.1"
+description = "Read metadata from Python packages"
+category = "main"
 optional = false
 python-versions = ">=3.6"
-version = "4.8.1"
 
 [package.dependencies]
+typing-extensions = {version = ">=3.6.4", markers = "python_version < \"3.8\""}
 zipp = ">=0.5"
 
-[package.dependencies.typing-extensions]
-python = "<3.8"
-version = ">=3.6.4"
-
 [package.extras]
 docs = ["sphinx", "jaraco.packaging (>=8.2)", "rst.linker (>=1.9)"]
 perf = ["ipython"]
 testing = ["pytest (>=4.6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytest-cov", "pytest-enabler (>=1.0.1)", "packaging", "pep517", "pyfakefs", "flufl.flake8", "pytest-perf (>=0.9.2)", "pytest-black (>=0.3.7)", "pytest-mypy", "importlib-resources (>=1.3)"]
 
 [[package]]
-category = "dev"
-description = "Read resources from Python packages"
-marker = "python_version < \"3.7\""
 name = "importlib-resources"
+version = "5.3.0"
+description = "Read resources from Python packages"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "5.3.0"
 
 [package.dependencies]
-[package.dependencies.zipp]
-python = "<3.10"
-version = ">=3.1.0"
+zipp = {version = ">=3.1.0", markers = "python_version < \"3.10\""}
 
 [package.extras]
 docs = ["sphinx", "jaraco.packaging (>=8.2)", "rst.linker (>=1.9)"]
 testing = ["pytest (>=6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytest-cov", "pytest-enabler (>=1.0.1)", "pytest-black (>=0.3.7)", "pytest-mypy"]
 
 [[package]]
-category = "dev"
-description = "iniconfig: brain-dead simple config-ini parsing"
 name = "iniconfig"
+version = "1.1.1"
+description = "iniconfig: brain-dead simple config-ini parsing"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.1.1"
 
 [[package]]
-category = "dev"
-description = "McCabe checker, plugin for flake8"
 name = "mccabe"
+version = "0.6.1"
+description = "McCabe checker, plugin for flake8"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "0.6.1"
 
 [[package]]
-category = "dev"
-description = "Optional static typing for Python"
 name = "mypy"
+version = "0.910"
+description = "Optional static typing for Python"
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "0.910"
 
 [package.dependencies]
 mypy-extensions = ">=0.4.3,<0.5.0"
 toml = "*"
+typed-ast = {version = ">=1.4.0,<1.5.0", markers = "python_version < \"3.8\""}
 typing-extensions = ">=3.7.4"
 
-[package.dependencies.typed-ast]
-python = "<3.8"
-version = ">=1.4.0,<1.5.0"
-
 [package.extras]
 dmypy = ["psutil (>=4.0)"]
 python2 = ["typed-ast (>=1.4.0,<1.5.0)"]
 
 [[package]]
-category = "dev"
-description = "Experimental type system extensions for programs checked with the mypy typechecker."
 name = "mypy-extensions"
+version = "0.4.3"
+description = "Experimental type system extensions for programs checked with the mypy typechecker."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "0.4.3"
 
 [[package]]
-category = "dev"
-description = "Node.js virtual environment builder"
 name = "nodeenv"
+version = "1.6.0"
+description = "Node.js virtual environment builder"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.6.0"
 
 [[package]]
-category = "dev"
-description = "Core utilities for Python packages"
 name = "packaging"
+version = "21.0"
+description = "Core utilities for Python packages"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "21.0"
 
 [package.dependencies]
 pyparsing = ">=2.0.2"
 
 [[package]]
-category = "dev"
-description = "Utility library for gitignore style pattern matching of file paths."
 name = "pathspec"
+version = "0.9.0"
+description = "Utility library for gitignore style pattern matching of file paths."
+category = "dev"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,>=2.7"
-version = "0.9.0"
 
 [[package]]
-category = "dev"
-description = "Python Build Reasonableness"
 name = "pbr"
+version = "5.6.0"
+description = "Python Build Reasonableness"
+category = "dev"
 optional = false
 python-versions = ">=2.6"
-version = "5.6.0"
 
 [[package]]
-category = "dev"
-description = "Check PEP-8 naming conventions, plugin for flake8"
 name = "pep8-naming"
+version = "0.12.1"
+description = "Check PEP-8 naming conventions, plugin for flake8"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "0.12.1"
 
 [package.dependencies]
 flake8 = ">=3.9.1"
 flake8-polyfill = ">=1.0.2,<2"
 
 [[package]]
-category = "dev"
-description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
 name = "platformdirs"
+version = "2.4.0"
+description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "2.4.0"
 
 [package.extras]
 docs = ["Sphinx (>=4)", "furo (>=2021.7.5b38)", "proselint (>=0.10.2)", "sphinx-autodoc-typehints (>=1.12)"]
-test = ["appdirs (1.4.4)", "pytest (>=6)", "pytest-cov (>=2.7)", "pytest-mock (>=3.6)"]
+test = ["appdirs (==1.4.4)", "pytest (>=6)", "pytest-cov (>=2.7)", "pytest-mock (>=3.6)"]
 
 [[package]]
-category = "dev"
-description = "plugin and hook calling mechanisms for python"
 name = "pluggy"
+version = "1.0.0"
+description = "plugin and hook calling mechanisms for python"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "1.0.0"
 
 [package.dependencies]
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12"
+importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
 
 [package.extras]
 dev = ["pre-commit", "tox"]
 testing = ["pytest", "pytest-benchmark"]
 
 [[package]]
-category = "dev"
-description = "A framework for managing and maintaining multi-language pre-commit hooks."
 name = "pre-commit"
+version = "2.15.0"
+description = "A framework for managing and maintaining multi-language pre-commit hooks."
+category = "dev"
 optional = false
 python-versions = ">=3.6.1"
-version = "2.15.0"
 
 [package.dependencies]
 cfgv = ">=2.0.0"
 identify = ">=1.0.0"
+importlib-metadata = {version = "*", markers = "python_version < \"3.8\""}
+importlib-resources = {version = "*", markers = "python_version < \"3.7\""}
 nodeenv = ">=0.11.1"
 pyyaml = ">=5.1"
 toml = "*"
 virtualenv = ">=20.0.8"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = "*"
-
-[package.dependencies.importlib-resources]
-python = "<3.7"
-version = "*"
-
 [[package]]
-category = "dev"
-description = "Some out-of-the-box hooks for pre-commit."
 name = "pre-commit-hooks"
+version = "4.0.1"
+description = "Some out-of-the-box hooks for pre-commit."
+category = "dev"
 optional = false
 python-versions = ">=3.6.1"
-version = "4.0.1"
 
 [package.dependencies]
 "ruamel.yaml" = ">=0.15"
 toml = "*"
 
 [[package]]
-category = "dev"
-description = "library with cross-python path, ini-parsing, io, code, log facilities"
 name = "py"
+version = "1.10.0"
+description = "library with cross-python path, ini-parsing, io, code, log facilities"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "1.10.0"
 
 [[package]]
-category = "dev"
-description = "Python style guide checker"
 name = "pycodestyle"
+version = "2.7.0"
+description = "Python style guide checker"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "2.7.0"
 
 [[package]]
-category = "dev"
-description = "Python docstring style checker"
+name = "pydantic"
+version = "1.8.2"
+description = "Data validation and settings management using python 3.6 type hinting"
+category = "main"
+optional = false
+python-versions = ">=3.6.1"
+
+[package.dependencies]
+dataclasses = {version = ">=0.6", markers = "python_version < \"3.7\""}
+typing-extensions = ">=3.7.4.3"
+
+[package.extras]
+dotenv = ["python-dotenv (>=0.10.4)"]
+email = ["email-validator (>=1.0.3)"]
+
+[[package]]
 name = "pydocstyle"
+version = "6.1.1"
+description = "Python docstring style checker"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "6.1.1"
 
 [package.dependencies]
 snowballstemmer = "*"
@@ -590,302 +567,274 @@ snowballstemmer = "*"
 toml = ["toml"]
 
 [[package]]
-category = "dev"
-description = "passive checker of Python programs"
 name = "pyflakes"
+version = "2.3.1"
+description = "passive checker of Python programs"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "2.3.1"
 
 [[package]]
-category = "dev"
-description = "Pygments is a syntax highlighting package written in Python."
 name = "pygments"
+version = "2.10.0"
+description = "Pygments is a syntax highlighting package written in Python."
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "2.10.0"
 
 [[package]]
-category = "dev"
-description = "Python parsing module"
 name = "pyparsing"
+version = "3.0.1"
+description = "Python parsing module"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "3.0.1"
 
 [package.extras]
 diagrams = ["jinja2", "railroad-diagrams"]
 
 [[package]]
-category = "dev"
-description = "pytest: simple powerful testing with Python"
 name = "pytest"
+version = "6.2.5"
+description = "pytest: simple powerful testing with Python"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "6.2.5"
 
 [package.dependencies]
-atomicwrites = ">=1.0"
+atomicwrites = {version = ">=1.0", markers = "sys_platform == \"win32\""}
 attrs = ">=19.2.0"
-colorama = "*"
+colorama = {version = "*", markers = "sys_platform == \"win32\""}
+importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
 iniconfig = "*"
 packaging = "*"
 pluggy = ">=0.12,<2.0"
 py = ">=1.8.2"
 toml = "*"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12"
-
 [package.extras]
 testing = ["argcomplete", "hypothesis (>=3.56)", "mock", "nose", "requests", "xmlschema"]
 
 [[package]]
-category = "dev"
-description = "YAML parser and emitter for Python"
 name = "pyyaml"
+version = "6.0"
+description = "YAML parser and emitter for Python"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "6.0"
 
 [[package]]
-category = "dev"
-description = "Alternative regular expression module, to replace re."
 name = "regex"
+version = "2021.10.23"
+description = "Alternative regular expression module, to replace re."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "2021.10.23"
 
 [[package]]
-category = "dev"
-description = "Tool for reordering python imports"
 name = "reorder-python-imports"
+version = "2.6.0"
+description = "Tool for reordering python imports"
+category = "dev"
 optional = false
 python-versions = ">=3.6.1"
-version = "2.6.0"
 
 [package.dependencies]
 "aspy.refactor-imports" = ">=2.1.0"
 
 [[package]]
-category = "dev"
-description = "Python HTTP for Humans."
 name = "requests"
+version = "2.26.0"
+description = "Python HTTP for Humans."
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*"
-version = "2.26.0"
 
 [package.dependencies]
 certifi = ">=2017.4.17"
+charset-normalizer = {version = ">=2.0.0,<2.1.0", markers = "python_version >= \"3\""}
+idna = {version = ">=2.5,<4", markers = "python_version >= \"3\""}
 urllib3 = ">=1.21.1,<1.27"
 
-[package.dependencies.charset-normalizer]
-python = ">=3"
-version = ">=2.0.0,<2.1.0"
-
-[package.dependencies.idna]
-python = ">=3"
-version = ">=2.5,<4"
-
 [package.extras]
-socks = ["PySocks (>=1.5.6,<1.5.7 || >1.5.7)", "win-inet-pton"]
+socks = ["PySocks (>=1.5.6,!=1.5.7)", "win-inet-pton"]
 use_chardet_on_py3 = ["chardet (>=3.0.2,<5)"]
 
 [[package]]
-category = "dev"
-description = "reStructuredText linter"
 name = "restructuredtext-lint"
+version = "1.3.2"
+description = "reStructuredText linter"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.3.2"
 
 [package.dependencies]
 docutils = ">=0.11,<1.0"
 
 [[package]]
-category = "dev"
-description = "ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order"
 name = "ruamel.yaml"
+version = "0.17.16"
+description = "ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order"
+category = "dev"
 optional = false
 python-versions = ">=3"
-version = "0.17.16"
 
 [package.dependencies]
-[package.dependencies."ruamel.yaml.clib"]
-python = "<3.10"
-version = ">=0.1.2"
+"ruamel.yaml.clib" = {version = ">=0.1.2", markers = "platform_python_implementation == \"CPython\" and python_version < \"3.10\""}
 
 [package.extras]
 docs = ["ryd"]
 jinja2 = ["ruamel.yaml.jinja2 (>=0.2)"]
 
 [[package]]
-category = "dev"
-description = "C version of reader, parser and emitter for ruamel.yaml derived from libyaml"
-marker = "platform_python_implementation == \"CPython\" and python_version < \"3.10\""
 name = "ruamel.yaml.clib"
+version = "0.2.6"
+description = "C version of reader, parser and emitter for ruamel.yaml derived from libyaml"
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "0.2.6"
 
 [[package]]
-category = "dev"
-description = "Checks installed dependencies for known vulnerabilities."
 name = "safety"
+version = "1.10.3"
+description = "Checks installed dependencies for known vulnerabilities."
+category = "dev"
 optional = false
 python-versions = ">=3.5"
-version = "1.10.3"
 
 [package.dependencies]
 Click = ">=6.0"
 dparse = ">=0.5.1"
 packaging = "*"
 requests = "*"
-setuptools = "*"
 
 [[package]]
-category = "dev"
-description = "Python 2 and 3 compatibility utilities"
 name = "six"
+version = "1.16.0"
+description = "Python 2 and 3 compatibility utilities"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*"
-version = "1.16.0"
 
 [[package]]
-category = "dev"
-description = "A pure Python implementation of a sliding window memory map manager"
 name = "smmap"
+version = "5.0.0"
+description = "A pure Python implementation of a sliding window memory map manager"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "5.0.0"
 
 [[package]]
-category = "dev"
-description = "This package provides 29 stemmers for 28 languages generated from Snowball algorithms."
 name = "snowballstemmer"
+version = "2.1.0"
+description = "This package provides 29 stemmers for 28 languages generated from Snowball algorithms."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "2.1.0"
 
 [[package]]
-category = "dev"
-description = "Manage dynamic plugins for Python applications"
 name = "stevedore"
+version = "3.5.0"
+description = "Manage dynamic plugins for Python applications"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
-version = "3.5.0"
 
 [package.dependencies]
+importlib-metadata = {version = ">=1.7.0", markers = "python_version < \"3.8\""}
 pbr = ">=2.0.0,<2.1.0 || >2.1.0"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=1.7.0"
-
 [[package]]
-category = "dev"
-description = "Python Library for Tom's Obvious, Minimal Language"
 name = "toml"
+version = "0.10.2"
+description = "Python Library for Tom's Obvious, Minimal Language"
+category = "dev"
 optional = false
 python-versions = ">=2.6, !=3.0.*, !=3.1.*, !=3.2.*"
-version = "0.10.2"
 
 [[package]]
-category = "dev"
-description = "a fork of Python 2 and 3 ast modules with type comment support"
 name = "typed-ast"
+version = "1.4.3"
+description = "a fork of Python 2 and 3 ast modules with type comment support"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.4.3"
 
 [[package]]
-category = "dev"
-description = "Run-time type checker for Python"
 name = "typeguard"
+version = "2.13.0"
+description = "Run-time type checker for Python"
+category = "dev"
 optional = false
 python-versions = ">=3.5.3"
-version = "2.13.0"
 
 [package.extras]
 doc = ["sphinx-rtd-theme", "sphinx-autodoc-typehints (>=1.2.0)"]
 test = ["pytest", "typing-extensions", "mypy"]
 
 [[package]]
-category = "dev"
-description = "Typing stubs for toml"
 name = "types-toml"
+version = "0.10.1"
+description = "Typing stubs for toml"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "0.10.1"
 
 [[package]]
-category = "main"
-description = "Backported and Experimental Type Hints for Python 3.5+"
 name = "typing-extensions"
+version = "3.10.0.2"
+description = "Backported and Experimental Type Hints for Python 3.5+"
+category = "main"
 optional = false
 python-versions = "*"
-version = "3.10.0.2"
 
 [[package]]
-category = "dev"
-description = "HTTP library with thread-safe connection pooling, file post, and more."
 name = "urllib3"
+version = "1.26.7"
+description = "HTTP library with thread-safe connection pooling, file post, and more."
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
-version = "1.26.7"
 
 [package.extras]
 brotli = ["brotlipy (>=0.6.0)"]
 secure = ["pyOpenSSL (>=0.14)", "cryptography (>=1.3.4)", "idna (>=2.0.0)", "certifi", "ipaddress"]
-socks = ["PySocks (>=1.5.6,<1.5.7 || >1.5.7,<2.0)"]
+socks = ["PySocks (>=1.5.6,!=1.5.7,<2.0)"]
 
 [[package]]
-category = "dev"
-description = "Virtual Python Environment builder"
 name = "virtualenv"
+version = "20.9.0"
+description = "Virtual Python Environment builder"
+category = "dev"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,>=2.7"
-version = "20.9.0"
 
 [package.dependencies]
 "backports.entry-points-selectable" = ">=1.0.4"
 distlib = ">=0.3.1,<1"
 filelock = ">=3.2,<4"
+importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
+importlib-resources = {version = ">=1.0", markers = "python_version < \"3.7\""}
 platformdirs = ">=2,<3"
 six = ">=1.9.0,<2"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12"
-
-[package.dependencies.importlib-resources]
-python = "<3.7"
-version = ">=1.0"
-
 [package.extras]
 docs = ["proselint (>=0.10.2)", "sphinx (>=3)", "sphinx-argparse (>=0.2.5)", "sphinx-rtd-theme (>=0.4.3)", "towncrier (>=19.9.0rc1)"]
 testing = ["coverage (>=4)", "coverage-enable-subprocess (>=1)", "flaky (>=3)", "pytest (>=4)", "pytest-env (>=0.6.2)", "pytest-freezegun (>=0.4.1)", "pytest-mock (>=2)", "pytest-randomly (>=1)", "pytest-timeout (>=1)", "packaging (>=20.0)"]
 
 [[package]]
-category = "dev"
-description = "A rewrite of the builtin doctest module"
 name = "xdoctest"
+version = "0.15.10"
+description = "A rewrite of the builtin doctest module"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "0.15.10"
 
 [package.dependencies]
+colorama = {version = "*", optional = true, markers = "platform_system == \"Windows\" and extra == \"colors\""}
+Pygments = {version = "*", optional = true, markers = "extra == \"colors\""}
 six = "*"
 
-[package.dependencies.Pygments]
-optional = true
-version = "*"
-
-[package.dependencies.colorama]
-optional = true
-version = "*"
-
 [package.extras]
 all = ["six", "codecov", "scikit-build", "cmake", "ninja", "pybind11", "pygments", "colorama", "pytest", "pytest", "pytest-cov", "pytest", "pytest", "pytest-cov", "typing", "nbformat", "nbconvert", "jupyter-client", "ipython", "ipykernel", "pytest", "pytest-cov"]
 colors = ["pygments", "colorama"]
@@ -894,22 +843,21 @@ optional = ["pygments", "colorama", "nbformat", "nbconvert", "jupyter-client", "
 tests = ["codecov", "scikit-build", "cmake", "ninja", "pybind11", "pytest", "pytest", "pytest-cov", "pytest", "pytest", "pytest-cov", "typing", "nbformat", "nbconvert", "jupyter-client", "ipython", "ipykernel", "pytest", "pytest-cov"]
 
 [[package]]
-category = "main"
-description = "Backport of pathlib-compatible object wrapper for zip files"
-marker = "python_version < \"3.8\""
 name = "zipp"
+version = "3.6.0"
+description = "Backport of pathlib-compatible object wrapper for zip files"
+category = "main"
 optional = false
 python-versions = ">=3.6"
-version = "3.6.0"
 
 [package.extras]
 docs = ["sphinx", "jaraco.packaging (>=8.2)", "rst.linker (>=1.9)"]
 testing = ["pytest (>=4.6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytest-cov", "pytest-enabler (>=1.0.1)", "jaraco.itertools", "func-timeout", "pytest-black (>=0.3.7)", "pytest-mypy"]
 
 [metadata]
-content-hash = "4dff7853f156825bae73d6ceca3284caa9eb02894e4b748b2cf00220f65a4e3e"
-lock-version = "1.0"
+lock-version = "1.1"
 python-versions = "^3.6.1"
+content-hash = "6985588fe2f184df65444747222242013b2fd5fcf98057b67220fd2d5fbd2e19"
 
 [metadata.files]
 appdirs = [
@@ -1169,6 +1117,30 @@ pycodestyle = [
     {file = "pycodestyle-2.7.0-py2.py3-none-any.whl", hash = "sha256:514f76d918fcc0b55c6680472f0a37970994e07bbb80725808c17089be302068"},
     {file = "pycodestyle-2.7.0.tar.gz", hash = "sha256:c389c1d06bf7904078ca03399a4816f974a1d590090fecea0c63ec26ebaf1cef"},
 ]
+pydantic = [
+    {file = "pydantic-1.8.2-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:05ddfd37c1720c392f4e0d43c484217b7521558302e7069ce8d318438d297739"},
+    {file = "pydantic-1.8.2-cp36-cp36m-manylinux1_i686.whl", hash = "sha256:a7c6002203fe2c5a1b5cbb141bb85060cbff88c2d78eccbc72d97eb7022c43e4"},
+    {file = "pydantic-1.8.2-cp36-cp36m-manylinux2014_i686.whl", hash = "sha256:589eb6cd6361e8ac341db97602eb7f354551482368a37f4fd086c0733548308e"},
+    {file = "pydantic-1.8.2-cp36-cp36m-manylinux2014_x86_64.whl", hash = "sha256:10e5622224245941efc193ad1d159887872776df7a8fd592ed746aa25d071840"},
+    {file = "pydantic-1.8.2-cp36-cp36m-win_amd64.whl", hash = "sha256:99a9fc39470010c45c161a1dc584997f1feb13f689ecf645f59bb4ba623e586b"},
+    {file = "pydantic-1.8.2-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:a83db7205f60c6a86f2c44a61791d993dff4b73135df1973ecd9eed5ea0bda20"},
+    {file = "pydantic-1.8.2-cp37-cp37m-manylinux1_i686.whl", hash = "sha256:41b542c0b3c42dc17da70554bc6f38cbc30d7066d2c2815a94499b5684582ecb"},
+    {file = "pydantic-1.8.2-cp37-cp37m-manylinux2014_i686.whl", hash = "sha256:ea5cb40a3b23b3265f6325727ddfc45141b08ed665458be8c6285e7b85bd73a1"},
+    {file = "pydantic-1.8.2-cp37-cp37m-manylinux2014_x86_64.whl", hash = "sha256:18b5ea242dd3e62dbf89b2b0ec9ba6c7b5abaf6af85b95a97b00279f65845a23"},
+    {file = "pydantic-1.8.2-cp37-cp37m-win_amd64.whl", hash = "sha256:234a6c19f1c14e25e362cb05c68afb7f183eb931dd3cd4605eafff055ebbf287"},
+    {file = "pydantic-1.8.2-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:021ea0e4133e8c824775a0cfe098677acf6fa5a3cbf9206a376eed3fc09302cd"},
+    {file = "pydantic-1.8.2-cp38-cp38-manylinux1_i686.whl", hash = "sha256:e710876437bc07bd414ff453ac8ec63d219e7690128d925c6e82889d674bb505"},
+    {file = "pydantic-1.8.2-cp38-cp38-manylinux2014_i686.whl", hash = "sha256:ac8eed4ca3bd3aadc58a13c2aa93cd8a884bcf21cb019f8cfecaae3b6ce3746e"},
+    {file = "pydantic-1.8.2-cp38-cp38-manylinux2014_x86_64.whl", hash = "sha256:4a03cbbe743e9c7247ceae6f0d8898f7a64bb65800a45cbdc52d65e370570820"},
+    {file = "pydantic-1.8.2-cp38-cp38-win_amd64.whl", hash = "sha256:8621559dcf5afacf0069ed194278f35c255dc1a1385c28b32dd6c110fd6531b3"},
+    {file = "pydantic-1.8.2-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:8b223557f9510cf0bfd8b01316bf6dd281cf41826607eada99662f5e4963f316"},
+    {file = "pydantic-1.8.2-cp39-cp39-manylinux1_i686.whl", hash = "sha256:244ad78eeb388a43b0c927e74d3af78008e944074b7d0f4f696ddd5b2af43c62"},
+    {file = "pydantic-1.8.2-cp39-cp39-manylinux2014_i686.whl", hash = "sha256:05ef5246a7ffd2ce12a619cbb29f3307b7c4509307b1b49f456657b43529dc6f"},
+    {file = "pydantic-1.8.2-cp39-cp39-manylinux2014_x86_64.whl", hash = "sha256:54cd5121383f4a461ff7644c7ca20c0419d58052db70d8791eacbbe31528916b"},
+    {file = "pydantic-1.8.2-cp39-cp39-win_amd64.whl", hash = "sha256:4be75bebf676a5f0f87937c6ddb061fa39cbea067240d98e298508c1bda6f3f3"},
+    {file = "pydantic-1.8.2-py3-none-any.whl", hash = "sha256:fec866a0b59f372b7e776f2d7308511784dace622e0992a0b59ea3ccee0ae833"},
+    {file = "pydantic-1.8.2.tar.gz", hash = "sha256:26464e57ccaafe72b7ad156fdaa4e9b9ef051f69e175dbbb463283000c05ab7b"},
+]
 pydocstyle = [
     {file = "pydocstyle-6.1.1-py3-none-any.whl", hash = "sha256:6987826d6775056839940041beef5c08cc7e3d71d63149b48e36727f70144dc4"},
     {file = "pydocstyle-6.1.1.tar.gz", hash = "sha256:1d41b7c459ba0ee6c345f2eb9ae827cab14a7533a88c5c6f7e94923f72df92dc"},
diff --git a/pyproject.toml b/pyproject.toml
index 82a8353..7d9b434 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "maison"
-version = "1.1.0"
+version = "1.2.0"
 description = "Maison"
 authors = ["Dom Batten <dominic.batten@googlemail.com>"]
 license = "MIT"
@@ -22,6 +22,7 @@ Changelog = "https://github.com/dbatten5/maison/releases"
 [tool.poetry.dependencies]
 python = "^3.6.1"
 click = "^8.0.1"
+pydantic = "^1.8.2"
 
 [tool.poetry.dev-dependencies]
 pytest = "^6.2.4"
diff --git a/src/maison/__init__.py b/src/maison/__init__.py
index 54c6e4d..5ebfeb9 100644
--- a/src/maison/__init__.py
+++ b/src/maison/__init__.py
@@ -1,2 +1,3 @@
 """Maison."""
 from .config import ProjectConfig
+from .schema import ConfigSchema
diff --git a/src/maison/config.py b/src/maison/config.py
index 3746638..7aa9e31 100644
--- a/src/maison/config.py
+++ b/src/maison/config.py
@@ -4,7 +4,9 @@
 from typing import Dict
 from typing import List
 from typing import Optional
+from typing import Type
 
+from maison.schema import ConfigSchema
 from maison.utils import _find_config
 
 
@@ -16,6 +18,7 @@ def __init__(
         project_name: str,
         starting_path: Optional[Path] = None,
         source_files: Optional[List[str]] = None,
+        schema: Optional[Type[ConfigSchema]] = None,
     ) -> None:
         """Initialize the config.
 
@@ -26,6 +29,7 @@ def __init__(
                 file
             source_files: an optional list of source config filenames to search for. If
                 none is provided then `pyproject.toml` will be used
+            schema: an optional `pydantic` model to define the config schema
         """
         self.source_files = source_files or ["pyproject.toml"]
         config_path, config_dict = _find_config(
@@ -35,6 +39,7 @@ def __init__(
         )
         self._config_dict: Dict[str, Any] = config_dict or {}
         self.config_path: Optional[Path] = config_path
+        self.schema = schema
 
     def __repr__(self) -> str:
         """Return the __repr__.
@@ -60,6 +65,45 @@ def to_dict(self) -> Dict[str, Any]:
         """
         return self._config_dict
 
+    def validate(
+        self,
+        schema: Optional[Type[ConfigSchema]] = None,
+        use_schema_values: bool = True,
+    ) -> None:
+        """Validate the configuration.
+
+        Note that this will cast values to whatever is defined in the schema. For
+        example, for the following schema:
+
+            class Schema(ConfigSchema):
+                foo: str
+
+        Validating a config with:
+
+            {"foo": 1}
+
+        Will result in:
+
+            {"foo": "1"}
+
+        Args:
+            schema: an optional `pydantic` base model to define the schema. This takes
+                precedence over a schema provided at object instantiation.
+            use_schema_values: an optional boolean to indicate whether the result
+                of passing the config through the schema should overwrite the existing
+                config values, meaning values are cast to types defined in the schema as
+                described above, and default values defined in the schema are used.
+        """
+        validated_schema: Optional[ConfigSchema] = None
+
+        if schema:
+            validated_schema = schema(**self._config_dict)
+        elif self.schema:
+            validated_schema = self.schema(**self._config_dict)
+
+        if validated_schema and use_schema_values:
+            self._config_dict = validated_schema.dict()
+
     def get_option(
         self, option_name: str, default_value: Optional[Any] = None
     ) -> Optional[Any]:
diff --git a/src/maison/schema.py b/src/maison/schema.py
new file mode 100644
index 0000000..bb6605d
--- /dev/null
+++ b/src/maison/schema.py
@@ -0,0 +1,6 @@
+"""Module to define the `ConfigSchema` class."""
+from pydantic import BaseModel
+
+
+class ConfigSchema(BaseModel):
+    """A class for creating schemas based on the `pydantic` `BaseModel`."""
diff --git a/tests/unit/test_config.py b/tests/unit/test_config.py
index 7321b73..83a8c5d 100644
--- a/tests/unit/test_config.py
+++ b/tests/unit/test_config.py
@@ -2,9 +2,12 @@
 from pathlib import Path
 from typing import Callable
 
+import pytest
 import toml
+from pydantic import ValidationError
 
 from maison.config import ProjectConfig
+from maison.schema import ConfigSchema
 
 
 class TestProjectConfig:
@@ -198,3 +201,165 @@ def test_valid_ini_file(self, create_tmp_file: Callable[..., Path]) -> None:
             "section 1": {"option_1": "value_1"},
             "section 2": {"option_2": "value_2"},
         }
+
+
+class TestValidation:
+    """Tests for schema validation."""
+
+    def test_no_schema(self) -> None:
+        """
+        Given an instance of `ProjectConfig` with no schema,
+        When the `validate` method is called,
+        Then nothing happens
+        """
+        config = ProjectConfig(project_name="acme", starting_path=Path("/"))
+
+        assert config.to_dict() == {}
+
+        config.validate()
+
+        assert config.to_dict() == {}
+
+    def test_one_schema_with_valid_config(
+        self,
+        create_tmp_file: Callable[..., Path],
+    ) -> None:
+        """
+        Given an instance of `ProjectConfig` with a given schema,
+        When the `validate` method is called,
+        Then the configuration is validated
+        """
+
+        class Schema(ConfigSchema):
+            """Defines schema."""
+
+            bar: str
+
+        config_toml = toml.dumps({"tool": {"foo": {"bar": "baz"}}})
+        pyproject_path = create_tmp_file(content=config_toml, filename="pyproject.toml")
+        config = ProjectConfig(
+            project_name="foo",
+            starting_path=pyproject_path,
+            schema=Schema,
+        )
+
+        config.validate()
+
+        assert config.get_option("bar") == "baz"
+
+    def test_use_schema_values(
+        self,
+        create_tmp_file: Callable[..., Path],
+    ) -> None:
+        """
+        Given an instance of `ProjectConfig` with a given schema,
+        When the `validate` method is called,
+        Then the configuration is validated and values are cast to those in the schema
+            and default values are used
+        """
+
+        class Schema(ConfigSchema):
+            """Defines schema."""
+
+            bar: str
+            other: str = "hello"
+
+        config_toml = toml.dumps({"tool": {"foo": {"bar": 1}}})
+        pyproject_path = create_tmp_file(content=config_toml, filename="pyproject.toml")
+        config = ProjectConfig(
+            project_name="foo",
+            starting_path=pyproject_path,
+            schema=Schema,
+        )
+
+        config.validate()
+
+        assert config.get_option("bar") == "1"
+        assert config.get_option("other") == "hello"
+
+    def test_not_use_schema_values(
+        self,
+        create_tmp_file: Callable[..., Path],
+    ) -> None:
+        """
+        Given an instance of `ProjectConfig` with a given schema,
+        When the `validate` method is called with `use_schema_values` set to `False`,
+        Then the configuration is validated but values remain as in the config
+        """
+
+        class Schema(ConfigSchema):
+            """Defines schema."""
+
+            bar: str
+            other: str = "hello"
+
+        config_toml = toml.dumps({"tool": {"foo": {"bar": 1}}})
+        pyproject_path = create_tmp_file(content=config_toml, filename="pyproject.toml")
+        config = ProjectConfig(
+            project_name="foo",
+            starting_path=pyproject_path,
+            schema=Schema,
+        )
+
+        config.validate(use_schema_values=False)
+
+        assert config.get_option("bar") == 1
+        assert config.get_option("other") is None
+
+    def test_schema_override(
+        self,
+        create_tmp_file: Callable[..., Path],
+    ) -> None:
+        """
+        Given an instance of `ProjectConfig` with a given schema,
+        When the `validate` method is called with a new schema,
+        Then the new schema is used
+        """
+
+        class Schema1(ConfigSchema):
+            """Defines schema for 1."""
+
+            bar: str = "schema_1"
+
+        class Schema2(ConfigSchema):
+            """Defines schema for 2."""
+
+            bar: str = "schema_2"
+
+        config_toml = toml.dumps({"tool": {"foo": {}}})
+        pyproject_path = create_tmp_file(content=config_toml, filename="pyproject.toml")
+        config = ProjectConfig(
+            project_name="foo",
+            starting_path=pyproject_path,
+            schema=Schema1,
+        )
+
+        config.validate(schema=Schema2)
+
+        assert config.get_option("bar") == "schema_2"
+
+    def test_invalid_configuration(
+        self,
+        create_tmp_file: Callable[..., Path],
+    ) -> None:
+        """
+        Given a configuration which doesn't conform to the schema,
+        When the `validate` method is called,
+        Then an error is raised
+        """
+
+        class Schema(ConfigSchema):
+            """Defines schema."""
+
+            bar: str
+
+        config_toml = toml.dumps({"tool": {"foo": {}}})
+        pyproject_path = create_tmp_file(content=config_toml, filename="pyproject.toml")
+        config = ProjectConfig(
+            project_name="foo",
+            starting_path=pyproject_path,
+            schema=Schema,
+        )
+
+        with pytest.raises(ValidationError):
+            config.validate()