diff --git a/proposals/README.md b/proposals/README.md
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+# WebGPU Extension Proposals
+
+The documents in this directory are
+[WebGPU extension documents](https://gpuweb.github.io/gpuweb/#extension-documents)
+which describe **non-normative, non-standardized draft proposals** to add functionality to WebGPU.
+
+These proposals **may or may not be under active consideration**.
+Check the "roadmap" of an extension document to understand its status.
+
+These proposals are **not stable** and may change at any time. They may be:
+
+- In-development proposals which are not easily contained in a GitHub pull request, HackMD, or similar.
+- Inactive proposals which are not under active consideration but could be considered later.
+
+If the group agrees that it never intends to consider a proposal in the future, it should be
+removed from this directory (and may be migrated outside of the WebGPU community group).
+
+## New Proposals
+
+Copy the format of an existing proposal. Proposals may be informal, as they are never normative.
+However, be sure to include a **detailed roadmap** to set expectations for developers, and, as
+appropriate, include:
+
+- WebGPU spec changes (including feature flags)
+- WGSL spec changes (including enable directives)
+- Links to context (like corresponding Vulkan/D3D12/Metal features) and past discussions
diff --git a/proposals/pipeline-statistics-query.md b/proposals/pipeline-statistics-query.md
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+# Pipeline Statistics Queries
+
+**Roadmap:** This extension is **not under active consideration**, but may be considered later.
+WebGPU implementations **must not** expose this functionality; doing so is a spec violation.
+Note however, an implementation might provide an option (e.g. command line flag) to enable a draft
+implementation, for developers who want to test this proposal or use its functionality for locally
+profiling their application performance.
+
+## WebGPU Spec Changes
+
+**Feature flags:** `"pipeline-statistics-query"`
+
+```
+partial dictionary GPUQuerySetDescriptor {
+    sequence<GPUPipelineStatisticName> pipelineStatistics = [];
+};
+
+enum GPUPipelineStatisticName {
+    "vertex-shader-invocations",
+    "clipper-invocations",
+    "clipper-primitives-out",
+    "fragment-shader-invocations",
+    "compute-shader-invocations",
+};
+
+partial interface GPUComputePassEncoder {
+    undefined beginPipelineStatisticsQuery(GPUQuerySet querySet, GPUSize32 queryIndex);
+    undefined endPipelineStatisticsQuery();
+};
+
+partial interface GPURenderPassEncoder {
+    undefined beginPipelineStatisticsQuery(GPUQuerySet querySet, GPUSize32 queryIndex);
+    undefined endPipelineStatisticsQuery();
+};
+```
+
+- `GPUQuerySetDescriptor.pipelineStatistics`:
+    The set of `GPUPipelineStatisticName` values in this sequence defines which pipeline statistics will be returned in the new query set.
+    - Must be empty if the query set type is not `"pipeline-statistics"`.
+    - Must not contain duplicate entries.
+- `beginPipelineStatisticsQuery(querySet, queryIndex)`:
+    Begins recording pipeline statistics to write into `querySet` at index `queryIndex`.
+    - If the feature is not enabled, throws a `TypeError`.
+    - Fails if a pipeline statistics query is already open.
+- `endPipelineStatisticsQuery()`:
+    Ends recording the current pipeline statistics query.
+    - If the feature is not enabled, throws a `TypeError`.
+    - Fails if a pipeline statistics query is not open.
+    - Fails if the pass is not open.
+- In `createQuerySet()`:
+    - If the query set type is `"pipeline-statistics"` but the feature is not enabled, throws a `TypeError`.
+- In `resolveQuerySet()`:
+    When resolving a pipeline statistics query, each result is written as a `GPUSize64`, and the number and order of the results written to GPU buffer matches the number and order of `GPUPipelineStatisticName`s specified in `GPUQuerySetDescriptor.pipelineStatistics`.
+- In `GPUComputePassEncoder`/`GPURenderPassEncoder`.`end()`:
+    - Fails if a pipeline statistics query is still open.
+
+## WGSL Spec Changes
+
+**Enable directive(s):** N/A
+
+## References
+
+- <https://github.com/gpuweb/gpuweb/issues/614>
+- <https://github.com/gpuweb/gpuweb/issues/794>
diff --git a/spec/index.bs b/spec/index.bs
index e3ad25e18a..b66d8917ae 100644
--- a/spec/index.bs
+++ b/spec/index.bs
@@ -1666,6 +1666,18 @@ interface GPUAdapterInfo {
     </div>
 </div>
 
+## Extension Documents ## {#extension-documents}
+
+"Extension Documents" are additional documents which describe new functionality which is
+non-normative and **not part of the WebGPU/WGSL specifications**.
+They describe functionality that builds upon these specifications, often including one or more new
+API [=feature=] flags and/or WGSL `enable` directives, or interactions with other draft
+web specifications.
+
+WebGPU implementations **must not** expose extension functionality; doing so is a spec violation.
+New functionality does not become part of the WebGPU standard until it is integrated
+into the WebGPU specification (this document) and/or WGSL specification.
+
 ## Origin Restrictions ## {#origin-restrictions}
 
 WebGPU allows accessing image data stored in images, videos, and canvases.