diff --git a/proposals/README.md b/proposals/README.md
index c424dc1880fbf..2bdf116092cee 100644
--- a/proposals/README.md
+++ b/proposals/README.md
@@ -26,6 +26,7 @@ request:
 -   [0029 - Linear, rebase, and pull-request GitHub workflow](p0029.md)
     -   [Decision](p0029_decision.md)
 -   [0042 - Create code review guidelines](p0042.md)
+    -   [Decision](p0042_decision.md)
 -   [0044 - Proposal tracking](p0044.md)
     -   [Decision](p0044_decision.md)
 -   [0051 - Goals](p0051.md)
@@ -33,6 +34,7 @@ request:
 -   [0074 - Change comment/decision timelines in proposal process](p0074.md)
     -   [Decision](p0074_decision.md)
 -   [0083 - In-progress design overview](p0083.md)
+    -   [Decision](p0083_decision.md)
 -   [0107 - Code and name organization](p0107.md)
 -   [0120 - Add idiomatic code performance and developer-facing docs to goals](p0120.md)
     -   [Decision](p0120_decision.md)
diff --git a/proposals/p0042_decision.md b/proposals/p0042_decision.md
new file mode 100644
index 0000000000000..e430613033427
--- /dev/null
+++ b/proposals/p0042_decision.md
@@ -0,0 +1,46 @@
+# Decision for: Create code review guidelines
+
+<!--
+Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+Exceptions. See /LICENSE for license information.
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+-->
+
+Proposal accepted on 2020-08-03
+
+Affirming:
+
+-   [austern](https://github.com/austern)
+-   [chandlerc](https://github.com/chandlerc)
+-   [geoffromer](https://github.com/geoffromer)
+-   [gribozavr](https://github.com/gribozavr)
+-   [zygoloid](https://github.com/zygoloid)
+
+Abstaining:
+
+-   [josh11b](https://github.com/josh11b)
+-   [noncombatant](https://github.com/noncombatant)
+-   [tituswinters](https://github.com/tituswinters)
+
+## Open questions
+
+There were no open questions.
+
+## Rationale
+
+This proposal contains the right goals for the code review process in light of
+our project goals, and the proposal is well-tailored to achieve them.
+Specifically:
+
+-   Ensure high quality of code, documentation, and other artifacts. We consider
+    these all "code reviews" regardless of whether the final artifact is "code"
+    in a technical sense.
+-   Encourage broad participation and contribution to the community through code
+    reviews.
+-   Ensure code reviews are inclusive, respectful, and welcoming.
+-   Have clear, discoverable, and mechanically enforced (where possible) rules
+    for who can, who should, and who must review any particular change.
+
+We want pre-commit rather than post-commit review, and we want all changes to go
+through review. These guidelines are consistent with standard code review best
+practice, including what’s described in the cited sources.