diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..7c51609
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,2 @@
+before_install:
+  - gem install bundler
\ No newline at end of file
diff --git a/lib/sinatra/param.rb b/lib/sinatra/param.rb
index 3609b78..1569163 100644
--- a/lib/sinatra/param.rb
+++ b/lib/sinatra/param.rb
@@ -159,9 +159,19 @@ def validate!(param, options)
         when :in, :within, :range
           raise InvalidParameterError, "Parameter must be within #{value}" unless param.nil? || case value
           when Range
-            value.include?(param)
+            case param
+            when Array
+              param.all? { |element| value.include?(element) }
+            else
+              value.include?(param)
+            end
           else
-            Array(value).include?(param)
+            case param
+            when Array
+              (param - Array(value)).empty?
+            else
+              Array(value).include?(param)
+            end
           end
         when :min
           raise InvalidParameterError, "Parameter cannot be less than #{value}" unless param.nil? || value <= param
diff --git a/spec/dummy/app.rb b/spec/dummy/app.rb
index a3ffc13..9790242 100644
--- a/spec/dummy/app.rb
+++ b/spec/dummy/app.rb
@@ -155,16 +155,31 @@ class App < Sinatra::Base
     params.to_json
   end
 
+  get '/validation/in/array' do
+    param :arg, Array, in: ['ASC', 'DESC']
+    params.to_json
+  end
+
   get '/validation/within' do
     param :arg, Integer, within: 1..10
     params.to_json
   end
 
+  get '/validation/within/array' do
+    param :arg, Array, within: 1..10, transform: ->(a) { a.map(&:to_i) }
+    params.to_json
+  end
+
   get '/validation/range' do
     param :arg, Integer, range: 1..10
     params.to_json
   end
 
+  get '/validation/range/array' do
+    param :arg, Array, range: 1..10, transform: ->(a) { a.map(&:to_i) }
+    params.to_json
+  end
+
   get '/validation/min' do
     param :arg, Integer, min: 12
     params.to_json
diff --git a/spec/parameter_validations_spec.rb b/spec/parameter_validations_spec.rb
index af5bdf1..56d9bfc 100644
--- a/spec/parameter_validations_spec.rb
+++ b/spec/parameter_validations_spec.rb
@@ -100,6 +100,21 @@
         expect(response.status).to eq(200)
       end
     end
+
+    describe 'for Arrays' do
+      it 'returns 400 on requests with any value not in the set' do
+        get('/validation/in/array', arg: 'MISC,ASC') do |response|
+          expect(response.status).to eq(400)
+          expect(JSON.parse(response.body)['message']).to eq("Parameter must be within [\"ASC\", \"DESC\"]")
+        end
+      end
+
+      it 'returns 200 on requests with all values in the set' do
+        get('/validation/in/array', arg: 'ASC,DESC') do |response|
+          expect(response.status).to eq(200)
+        end
+      end
+    end
   end
 
   describe 'within' do
@@ -115,6 +130,21 @@
         expect(response.status).to eq(200)
       end
     end
+
+    describe 'for Arrays' do
+      it 'returns 400 on requests with any value outside the range' do
+        get('/validation/within/array', arg: [20,5]) do |response|
+          expect(response.status).to eq(400)
+          expect(JSON.parse(response.body)['message']).to eq("Parameter must be within 1..10")
+        end
+      end
+
+      it 'returns 200 on requests with all values within the range' do
+        get('/validation/within/array', arg: [5,10]) do |response|
+          expect(response.status).to eq(200)
+        end
+      end
+    end
   end
 
   describe 'range' do
@@ -130,6 +160,21 @@
         expect(response.status).to eq(200)
       end
     end
+
+    describe 'for Arrays' do
+      it 'returns 400 on requests with any value outside the range' do
+        get('/validation/range/array', arg: [20,5]) do |response|
+          expect(response.status).to eq(400)
+          expect(JSON.parse(response.body)['message']).to eq("Parameter must be within 1..10")
+        end
+      end
+
+      it 'returns 200 on requests with all values within the range' do
+        get('/validation/range/array', arg: [5,10]) do |response|
+          expect(response.status).to eq(200)
+        end
+      end
+    end
   end
 
   describe 'min' do