diff --git a/CHANGES.md b/CHANGES.md
index 8a023b769..6eecb5683 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,64 @@
+Synapse 1.66.0rc1 (2022-08-23)
+==============================
+
+Features
+--------
+
+- Improve validation of request bodies for the following client-server API endpoints: [`/account/password`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpassword), [`/account/password/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpasswordemailrequesttoken), [`/account/deactivate`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountdeactivate) and [`/account/3pid/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidemailrequesttoken). ([\#13188](https://github.com/matrix-org/synapse/issues/13188), [\#13563](https://github.com/matrix-org/synapse/issues/13563))
+- Add forgotten status to Room Details API. ([\#13503](https://github.com/matrix-org/synapse/issues/13503))
+- Add an experimental implementation for [MSC3852](https://github.com/matrix-org/matrix-spec-proposals/pull/3852). ([\#13549](https://github.com/matrix-org/synapse/issues/13549))
+- Add `org.matrix.msc2716v4` experimental room version with updated content fields. ([\#13551](https://github.com/matrix-org/synapse/issues/13551))
+
+
+Bugfixes
+--------
+
+- Faster room joins: make `/joined_members` block whilst the room is partial stated. ([\#13514](https://github.com/matrix-org/synapse/issues/13514))
+- Fix a bug in the `/event_reports` Admin API which meant that the total count could be larger than the number of results you can actually query for. ([\#13525](https://github.com/matrix-org/synapse/issues/13525))
+- Add support for compression to federation responses. ([\#13537](https://github.com/matrix-org/synapse/issues/13537))
+- Fix a bug introduced in Synapse 1.52.0 where sending server notices fails if `max_avatar_size` or `allowed_avatar_mimetypes` is set and not `system_mxid_avatar_url`. ([\#13566](https://github.com/matrix-org/synapse/issues/13566))
+- Fix the `opentracing.force_tracing_for_users` config option not applying to [`/sendToDevice`](https://spec.matrix.org/v1.3/client-server-api/#put_matrixclientv3sendtodeviceeventtypetxnid) and [`/keys/upload`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3keysupload) requests. ([\#13574](https://github.com/matrix-org/synapse/issues/13574))
+
+
+Improved Documentation
+----------------------
+
+- Add `openssl` example for generating registration HMAC digest. ([\#13472](https://github.com/matrix-org/synapse/issues/13472))
+- Tidy up Synapse's README. ([\#13491](https://github.com/matrix-org/synapse/issues/13491))
+- Document that event purging related to the `redaction_retention_period` config option is executed only every 5 minutes. ([\#13492](https://github.com/matrix-org/synapse/issues/13492))
+- Add a warning to retention documentation regarding the possibility of database corruption. ([\#13497](https://github.com/matrix-org/synapse/issues/13497))
+- Document that the `DOCKER_BUILDKIT=1` flag is needed to build the docker image. ([\#13515](https://github.com/matrix-org/synapse/issues/13515))
+- Add missing links in `user_consent` section of configuration manual. ([\#13536](https://github.com/matrix-org/synapse/issues/13536))
+- Fix the doc and some warnings that were referring to the nonexistent `custom_templates_directory` setting (instead of `custom_template_directory`). ([\#13538](https://github.com/matrix-org/synapse/issues/13538))
+
+
+Internal Changes
+----------------
+
+- Refactor methods in `synapse.api.auth.Auth` to use `Requester` objects everywhere instead of user IDs. ([\#13024](https://github.com/matrix-org/synapse/issues/13024))
+- Allow use of both `@trace` and `@tag_args` stacked on the same function (tracing). ([\#13453](https://github.com/matrix-org/synapse/issues/13453))
+- Faster joins: update the rejected state of events during de-partial-stating. ([\#13459](https://github.com/matrix-org/synapse/issues/13459))
+- Clean-up tests for notifications. ([\#13471](https://github.com/matrix-org/synapse/issues/13471))
+- Add some miscellaneous comments to document sync, especially around `compute_state_delta`. ([\#13474](https://github.com/matrix-org/synapse/issues/13474))
+- Faster room joins: Avoid blocking lazy-loading `/sync`s during partial joins due to remote memberships. Pull remote memberships from auth events instead of the room state. ([\#13477](https://github.com/matrix-org/synapse/issues/13477))
+- Use literals in place of `HTTPStatus` constants in tests. ([\#13479](https://github.com/matrix-org/synapse/issues/13479), [\#13488](https://github.com/matrix-org/synapse/issues/13488))
+- Add comments about how event push actions are rotated. ([\#13485](https://github.com/matrix-org/synapse/issues/13485))
+- Instrument the federation/backfill part of `/messages` for understandable traces in Jaeger. ([\#13489](https://github.com/matrix-org/synapse/issues/13489))
+- Modify HTML template content to better support mobile devices' screen sizes. ([\#13493](https://github.com/matrix-org/synapse/issues/13493))
+- Instrument `FederationStateIdsServlet` (`/state_ids`) for understandable traces in Jaeger. ([\#13499](https://github.com/matrix-org/synapse/issues/13499), [\#13554](https://github.com/matrix-org/synapse/issues/13554))
+- Add a linter script which will reject non-strict types in Pydantic models. ([\#13502](https://github.com/matrix-org/synapse/issues/13502))
+- Improve performance of sending messages in rooms with thousands of local users. ([\#13522](https://github.com/matrix-org/synapse/issues/13522), [\#13547](https://github.com/matrix-org/synapse/issues/13547))
+- Faster room joins: Refuse to start when faster joins is enabled on a deployment with workers, since worker configurations are not currently supported. ([\#13531](https://github.com/matrix-org/synapse/issues/13531))
+- Track HTTP response times over 10 seconds from `/messages` (`synapse_room_message_list_rest_servlet_response_time_seconds`). ([\#13533](https://github.com/matrix-org/synapse/issues/13533))
+- Add metrics to track how the rate limiter is affecting requests (sleep/reject). ([\#13534](https://github.com/matrix-org/synapse/issues/13534), [\#13541](https://github.com/matrix-org/synapse/issues/13541))
+- Add metrics to time how long it takes us to do backfill processing (`synapse_federation_backfill_processing_before_time_seconds`, `synapse_federation_backfill_processing_after_time_seconds`). ([\#13535](https://github.com/matrix-org/synapse/issues/13535), [\#13584](https://github.com/matrix-org/synapse/issues/13584))
+- Reduce the number of tests using legacy TCP replication. ([\#13543](https://github.com/matrix-org/synapse/issues/13543))
+- Add metrics to track rate limiter queue timing (`synapse_rate_limit_queue_wait_time_seconds`). ([\#13544](https://github.com/matrix-org/synapse/issues/13544))
+- Update metrics to track `/messages` response time by room size. ([\#13545](https://github.com/matrix-org/synapse/issues/13545))
+- Allow specifying additional request fields when using the `HomeServerTestCase.login` helper method. ([\#13549](https://github.com/matrix-org/synapse/issues/13549))
+- Make `HomeServerTestCase` load any configured homeserver modules automatically. ([\#13558](https://github.com/matrix-org/synapse/issues/13558))
+
+
 Synapse 1.65.0 (2022-08-16)
 ===========================
 
diff --git a/changelog.d/13024.misc b/changelog.d/13024.misc
deleted file mode 100644
index aa43c8242..000000000
--- a/changelog.d/13024.misc
+++ /dev/null
@@ -1 +0,0 @@
-Refactor methods in `synapse.api.auth.Auth` to use `Requester` objects everywhere instead of user IDs.
diff --git a/changelog.d/13188.feature b/changelog.d/13188.feature
deleted file mode 100644
index 4c39b7428..000000000
--- a/changelog.d/13188.feature
+++ /dev/null
@@ -1 +0,0 @@
-Improve validation of request bodies for the following client-server API endpoints: [`/account/password`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpassword), [`/account/password/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpasswordemailrequesttoken), [`/account/deactivate`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountdeactivate) and [`/account/3pid/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidemailrequesttoken).
diff --git a/changelog.d/13453.misc b/changelog.d/13453.misc
deleted file mode 100644
index d30c5230c..000000000
--- a/changelog.d/13453.misc
+++ /dev/null
@@ -1 +0,0 @@
-Allow use of both `@trace` and `@tag_args` stacked on the same function (tracing).
diff --git a/changelog.d/13459.misc b/changelog.d/13459.misc
deleted file mode 100644
index e6082210a..000000000
--- a/changelog.d/13459.misc
+++ /dev/null
@@ -1 +0,0 @@
-Faster joins: update the rejected state of events during de-partial-stating.
diff --git a/changelog.d/13471.misc b/changelog.d/13471.misc
deleted file mode 100644
index b55ff32c7..000000000
--- a/changelog.d/13471.misc
+++ /dev/null
@@ -1 +0,0 @@
-Clean-up tests for notifications.
diff --git a/changelog.d/13472.doc b/changelog.d/13472.doc
deleted file mode 100644
index 2ff631730..000000000
--- a/changelog.d/13472.doc
+++ /dev/null
@@ -1 +0,0 @@
-Add `openssl` example for generating registration HMAC digest.
diff --git a/changelog.d/13474.misc b/changelog.d/13474.misc
deleted file mode 100644
index d34c661fe..000000000
--- a/changelog.d/13474.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add some miscellaneous comments to document sync, especially around `compute_state_delta`.
diff --git a/changelog.d/13477.misc b/changelog.d/13477.misc
deleted file mode 100644
index 5d21ae9d7..000000000
--- a/changelog.d/13477.misc
+++ /dev/null
@@ -1 +0,0 @@
-Faster room joins: Avoid blocking lazy-loading `/sync`s during partial joins due to remote memberships. Pull remote memberships from auth events instead of the room state.
diff --git a/changelog.d/13479.misc b/changelog.d/13479.misc
deleted file mode 100644
index 315930dea..000000000
--- a/changelog.d/13479.misc
+++ /dev/null
@@ -1 +0,0 @@
-Use literals in place of `HTTPStatus` constants in tests.
\ No newline at end of file
diff --git a/changelog.d/13485.misc b/changelog.d/13485.misc
deleted file mode 100644
index c75712b9f..000000000
--- a/changelog.d/13485.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add comments about how event push actions are rotated.
diff --git a/changelog.d/13488.misc b/changelog.d/13488.misc
deleted file mode 100644
index 315930dea..000000000
--- a/changelog.d/13488.misc
+++ /dev/null
@@ -1 +0,0 @@
-Use literals in place of `HTTPStatus` constants in tests.
\ No newline at end of file
diff --git a/changelog.d/13489.misc b/changelog.d/13489.misc
deleted file mode 100644
index 5e4853860..000000000
--- a/changelog.d/13489.misc
+++ /dev/null
@@ -1 +0,0 @@
-Instrument the federation/backfill part of `/messages` for understandable traces in Jaeger.
diff --git a/changelog.d/13491.doc b/changelog.d/13491.doc
deleted file mode 100644
index 026f73554..000000000
--- a/changelog.d/13491.doc
+++ /dev/null
@@ -1 +0,0 @@
-Tidy up Synapse's README.
diff --git a/changelog.d/13492.doc b/changelog.d/13492.doc
deleted file mode 100644
index fc4850d55..000000000
--- a/changelog.d/13492.doc
+++ /dev/null
@@ -1 +0,0 @@
-Document that event purging related to the `redaction_retention_period` config option is executed only every 5 minutes.
diff --git a/changelog.d/13493.misc b/changelog.d/13493.misc
deleted file mode 100644
index d7d5c33a8..000000000
--- a/changelog.d/13493.misc
+++ /dev/null
@@ -1 +0,0 @@
-Modify HTML template content to better support mobile devices' screen sizes.
\ No newline at end of file
diff --git a/changelog.d/13497.doc b/changelog.d/13497.doc
deleted file mode 100644
index ef6dc2308..000000000
--- a/changelog.d/13497.doc
+++ /dev/null
@@ -1,2 +0,0 @@
-Add a warning to retention documentation regarding the possibility of database corruption.
-
diff --git a/changelog.d/13499.misc b/changelog.d/13499.misc
deleted file mode 100644
index 99dbcebec..000000000
--- a/changelog.d/13499.misc
+++ /dev/null
@@ -1 +0,0 @@
-Instrument `FederationStateIdsServlet` (`/state_ids`) for understandable traces in Jaeger.
diff --git a/changelog.d/13502.misc b/changelog.d/13502.misc
deleted file mode 100644
index ed6832996..000000000
--- a/changelog.d/13502.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add a linter script which will reject non-strict types in Pydantic models.
diff --git a/changelog.d/13503.feature b/changelog.d/13503.feature
deleted file mode 100644
index 4baabd1e3..000000000
--- a/changelog.d/13503.feature
+++ /dev/null
@@ -1 +0,0 @@
-Add forgotten status to Room Details API.
\ No newline at end of file
diff --git a/changelog.d/13514.bugfix b/changelog.d/13514.bugfix
deleted file mode 100644
index 7498af0e4..000000000
--- a/changelog.d/13514.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Faster room joins: make `/joined_members` block whilst the room is partial stated.
\ No newline at end of file
diff --git a/changelog.d/13515.doc b/changelog.d/13515.doc
deleted file mode 100644
index a4d9d97dc..000000000
--- a/changelog.d/13515.doc
+++ /dev/null
@@ -1 +0,0 @@
-Document that the `DOCKER_BUILDKIT=1` flag is needed to build the docker image.
\ No newline at end of file
diff --git a/changelog.d/13522.misc b/changelog.d/13522.misc
deleted file mode 100644
index 0a8827205..000000000
--- a/changelog.d/13522.misc
+++ /dev/null
@@ -1 +0,0 @@
-Improve performance of sending messages in rooms with thousands of local users.
diff --git a/changelog.d/13525.bugfix b/changelog.d/13525.bugfix
deleted file mode 100644
index dbd1adbc8..000000000
--- a/changelog.d/13525.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix a bug in the `/event_reports` Admin API which meant that the total count could be larger than the number of results you can actually query for.
\ No newline at end of file
diff --git a/changelog.d/13531.misc b/changelog.d/13531.misc
deleted file mode 100644
index 986122d3d..000000000
--- a/changelog.d/13531.misc
+++ /dev/null
@@ -1 +0,0 @@
-Faster room joins: Refuse to start when faster joins is enabled on a deployment with workers, since worker configurations are not currently supported.
diff --git a/changelog.d/13533.misc b/changelog.d/13533.misc
deleted file mode 100644
index ab4b18887..000000000
--- a/changelog.d/13533.misc
+++ /dev/null
@@ -1 +0,0 @@
-Track HTTP response times over 10 seconds from `/messages` (`synapse_room_message_list_rest_servlet_response_time_seconds`).
diff --git a/changelog.d/13534.misc b/changelog.d/13534.misc
deleted file mode 100644
index b488bf74c..000000000
--- a/changelog.d/13534.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add metrics to track how the rate limiter is affecting requests (sleep/reject).
diff --git a/changelog.d/13535.misc b/changelog.d/13535.misc
deleted file mode 100644
index 6b190181c..000000000
--- a/changelog.d/13535.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add metrics to time how long it takes us to do backfill processing (`synapse_federation_backfill_processing_before_time_seconds`, `synapse_federation_backfill_processing_after_time_seconds`).
diff --git a/changelog.d/13536.doc b/changelog.d/13536.doc
deleted file mode 100644
index c8752acb7..000000000
--- a/changelog.d/13536.doc
+++ /dev/null
@@ -1 +0,0 @@
-Add missing links in `user_consent` section of configuration manual.
diff --git a/changelog.d/13537.bugfix b/changelog.d/13537.bugfix
deleted file mode 100644
index db843504b..000000000
--- a/changelog.d/13537.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Add support for compression to federation responses.
diff --git a/changelog.d/13538.doc b/changelog.d/13538.doc
deleted file mode 100644
index 9215aeac5..000000000
--- a/changelog.d/13538.doc
+++ /dev/null
@@ -1 +0,0 @@
-Fix the doc and some warnings that were referring to the nonexistent `custom_templates_directory` setting (instead of `custom_template_directory`).
\ No newline at end of file
diff --git a/changelog.d/13541.misc b/changelog.d/13541.misc
deleted file mode 100644
index b488bf74c..000000000
--- a/changelog.d/13541.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add metrics to track how the rate limiter is affecting requests (sleep/reject).
diff --git a/changelog.d/13543.misc b/changelog.d/13543.misc
deleted file mode 100644
index 0300f46cd..000000000
--- a/changelog.d/13543.misc
+++ /dev/null
@@ -1 +0,0 @@
-Reduce the number of tests using legacy TCP replication.
diff --git a/changelog.d/13544.misc b/changelog.d/13544.misc
deleted file mode 100644
index d84ba3f07..000000000
--- a/changelog.d/13544.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add metrics to track rate limiter queue timing (`synapse_rate_limit_queue_wait_time_seconds`).
diff --git a/changelog.d/13545.misc b/changelog.d/13545.misc
deleted file mode 100644
index 1cdbef179..000000000
--- a/changelog.d/13545.misc
+++ /dev/null
@@ -1 +0,0 @@
-Update metrics to track `/messages` response time by room size.
diff --git a/changelog.d/13547.misc b/changelog.d/13547.misc
deleted file mode 100644
index 0a8827205..000000000
--- a/changelog.d/13547.misc
+++ /dev/null
@@ -1 +0,0 @@
-Improve performance of sending messages in rooms with thousands of local users.
diff --git a/changelog.d/13549.feature b/changelog.d/13549.feature
deleted file mode 100644
index b6a726789..000000000
--- a/changelog.d/13549.feature
+++ /dev/null
@@ -1 +0,0 @@
-Add an experimental implementation for [MSC3852](https://github.com/matrix-org/matrix-spec-proposals/pull/3852).
\ No newline at end of file
diff --git a/changelog.d/13549.misc b/changelog.d/13549.misc
deleted file mode 100644
index 5b4303e87..000000000
--- a/changelog.d/13549.misc
+++ /dev/null
@@ -1 +0,0 @@
-Allow specifying additional request fields when using the `HomeServerTestCase.login` helper method.
\ No newline at end of file
diff --git a/changelog.d/13551.feature b/changelog.d/13551.feature
deleted file mode 100644
index 365673a3c..000000000
--- a/changelog.d/13551.feature
+++ /dev/null
@@ -1 +0,0 @@
-Add `org.matrix.msc2716v4` experimental room version with updated content fields.
diff --git a/changelog.d/13554.misc b/changelog.d/13554.misc
deleted file mode 100644
index 99dbcebec..000000000
--- a/changelog.d/13554.misc
+++ /dev/null
@@ -1 +0,0 @@
-Instrument `FederationStateIdsServlet` (`/state_ids`) for understandable traces in Jaeger.
diff --git a/changelog.d/13558.misc b/changelog.d/13558.misc
deleted file mode 100644
index e3f3e3174..000000000
--- a/changelog.d/13558.misc
+++ /dev/null
@@ -1 +0,0 @@
-Make `HomeServerTestCase` load any configured homeserver modules automatically.
\ No newline at end of file
diff --git a/changelog.d/13563.feature b/changelog.d/13563.feature
deleted file mode 100644
index 4c39b7428..000000000
--- a/changelog.d/13563.feature
+++ /dev/null
@@ -1 +0,0 @@
-Improve validation of request bodies for the following client-server API endpoints: [`/account/password`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpassword), [`/account/password/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpasswordemailrequesttoken), [`/account/deactivate`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountdeactivate) and [`/account/3pid/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidemailrequesttoken).
diff --git a/changelog.d/13566.bugfix b/changelog.d/13566.bugfix
deleted file mode 100644
index 6c44024ad..000000000
--- a/changelog.d/13566.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix a bug introduced in Synapse 1.52.0 where sending server notices fails if `max_avatar_size` or `allowed_avatar_mimetypes` is set and not `system_mxid_avatar_url`.
\ No newline at end of file
diff --git a/changelog.d/13574.bugfix b/changelog.d/13574.bugfix
deleted file mode 100644
index 3899c137a..000000000
--- a/changelog.d/13574.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix the `opentracing.force_tracing_for_users` config option not applying to [`/sendToDevice`](https://spec.matrix.org/v1.3/client-server-api/#put_matrixclientv3sendtodeviceeventtypetxnid) and [`/keys/upload`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3keysupload) requests.
\ No newline at end of file
diff --git a/changelog.d/13584.misc b/changelog.d/13584.misc
deleted file mode 100644
index 6b190181c..000000000
--- a/changelog.d/13584.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add metrics to time how long it takes us to do backfill processing (`synapse_federation_backfill_processing_before_time_seconds`, `synapse_federation_backfill_processing_after_time_seconds`).
diff --git a/debian/changelog b/debian/changelog
index 917249f94..c3974261a 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+matrix-synapse-py3 (1.66.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.66.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 23 Aug 2022 09:48:55 +0100
+
 matrix-synapse-py3 (1.65.0) stable; urgency=medium
 
   * New Synapse release 1.65.0.
diff --git a/pyproject.toml b/pyproject.toml
index 9e59470ac..745b6067a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -54,7 +54,7 @@ skip_gitignore = true
 
 [tool.poetry]
 name = "matrix-synapse"
-version = "1.65.0"
+version = "1.66.0rc1"
 description = "Homeserver for the Matrix decentralised comms protocol"
 authors = ["Matrix.org Team and Contributors <packages@matrix.org>"]
 license = "Apache-2.0"