diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 2c8e529a4fa..25a27c3da8c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -270,6 +270,26 @@ Tests in staging do not count towards the test262 coverage requirement for a TC3
 Implementations may designate a group of people who have permission to review and land tests in the staging folder.
 To add or remove people from this group, please open an issue.
 
+## Implementation Contributed
+
+There is a `test/implementation-contributed/` folder, containing tests that are subject to fewer requirements, in order to promote sharing of tests between implementations.
+
+Tests in implementation-contributed are not required to be split up into one test per file, or to conform to any particular style as long as they are runnable.
+In particular, mechanically-converted tests from implementations' private test suites are encouraged, as sharing them with other implementations promotes interoperability.
+
+These are the requirements for adding a test to staging:
+
+1. Just as with a test outside of staging, it must test an existing language feature, a Stage 3 TC39 proposal, or a normative pull request.
+2. It is correct.
+3. It is runnable using the usual test262 runner.
+4. It is reviewed by someone with permission to land tests in the staging folder, not necessarily a test262 maintainer.
+5. If it requires the implementation to support ECMA-402, it must be in `test/staging/intl402/` or a subfolder thereof.
+
+Tests in staging do not count towards the test262 coverage requirement for a TC39 proposal to reach Stage 4.
+
+Implementations may designate a group of people who have permission to review and land tests in the implementation-contributed folder.
+To add or remove people from this group, please open an issue.
+
 ## Test Environment
 
 Each test case is run in a fresh JavaScript environment; in a browser, this will be a new <iframe>; for a console runner, this will be a new process.
@@ -298,8 +318,8 @@ function Test262Error(message) {
 
 The [Module section of INTERPRETING.md](https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md#modules) states that `_FIXTURE` files will not have Realm modifications applied. In practice, this means that code in `_FIXTURE` files must abide by the following rules:
 
-- **MUST NOT** refer to, or make use of any [Test262-Defined Bindings](https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md#test262-defined-bindings) in any way. 
-- **MUST NOT** refer to, or make use of any [Host-Defined Functions](https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md#host-defined-functions) in any way. 
+- **MUST NOT** refer to, or make use of any [Test262-Defined Bindings](https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md#test262-defined-bindings) in any way.
+- **MUST NOT** refer to, or make use of any [Host-Defined Functions](https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md#host-defined-functions) in any way.
 
 ## Handling Errors and Negative Test Cases