diff --git a/doc/manual/source/SUMMARY.md.in b/doc/manual/source/SUMMARY.md.in
index 374aacb59..dd3218d2f 100644
--- a/doc/manual/source/SUMMARY.md.in
+++ b/doc/manual/source/SUMMARY.md.in
@@ -129,6 +129,7 @@
   - [Contributing](development/contributing.md)
 - [Determinate Nix Release Notes](release-notes-determinate/index.md)
   - [Changes between Nix and Determinate Nix](release-notes-determinate/changes.md)<!-- next -->
+  - [Release 3.6.6 (2025-06-17)](release-notes-determinate/rl-3.6.6.md)
   - [Release 3.6.5 (2025-06-16)](release-notes-determinate/rl-3.6.5.md)
   - [Release 3.6.2 (2025-06-02)](release-notes-determinate/rl-3.6.2.md)
   - [Release 3.6.1 (2025-05-24)](release-notes-determinate/rl-3.6.1.md)
diff --git a/doc/manual/source/release-notes-determinate/changes.md b/doc/manual/source/release-notes-determinate/changes.md
index 30a68f6e9..a86b16a70 100644
--- a/doc/manual/source/release-notes-determinate/changes.md
+++ b/doc/manual/source/release-notes-determinate/changes.md
@@ -1,6 +1,6 @@
 # Changes between Nix and Determinate Nix
 
-This section lists the differences between upstream Nix 2.29 and Determinate Nix 3.6.5.<!-- differences -->
+This section lists the differences between upstream Nix 2.29 and Determinate Nix 3.6.6.<!-- differences -->
 
 * In Determinate Nix, flakes are stable. You no longer need to enable the `flakes` experimental feature.
 
@@ -72,3 +72,23 @@ This section lists the differences between upstream Nix 2.29 and Determinate Nix
 * Improve error messages that use the hypothetical future tense of "will" by @lucperkins in [DeterminateSystems/nix-src#92](https://github.com/DeterminateSystems/nix-src/pull/92)
 
 * Improve caching of inputs in dry-run mode by @edolstra in [DeterminateSystems/nix-src#98](https://github.com/DeterminateSystems/nix-src/pull/98)
+
+<!-- Determinate Nix version 3.6.6 -->
+
+* Release v3.6.4 by @github-actions in [DeterminateSystems/nix-src#109](https://github.com/DeterminateSystems/nix-src/pull/109)
+
+* Fixup the complainy docs line by @grahamc in [DeterminateSystems/nix-src#111](https://github.com/DeterminateSystems/nix-src/pull/111)
+
+* Move the actual vm tests / flake regressions into the generic build phase by @grahamc in [DeterminateSystems/nix-src#112](https://github.com/DeterminateSystems/nix-src/pull/112)
+
+* Fix broken fetchToStore() caching by @edolstra in [DeterminateSystems/nix-src#110](https://github.com/DeterminateSystems/nix-src/pull/110)
+
+* Parallelize the flake regression suite by @grahamc in [DeterminateSystems/nix-src#114](https://github.com/DeterminateSystems/nix-src/pull/114)
+
+* Don't build fallback-paths if we didn't build aarch64-linux and x86 d…   …arwin by @grahamc in [DeterminateSystems/nix-src#116](https://github.com/DeterminateSystems/nix-src/pull/116)
+
+* Use GHA runners for VMs since they have KVM by @grahamc in [DeterminateSystems/nix-src#118](https://github.com/DeterminateSystems/nix-src/pull/118)
+
+* fetchToStore() cache: Use content hashes instead of store paths by @edolstra in [DeterminateSystems/nix-src#115](https://github.com/DeterminateSystems/nix-src/pull/115)
+
+* Release v3.6.5 by @github-actions in [DeterminateSystems/nix-src#119](https://github.com/DeterminateSystems/nix-src/pull/119)
diff --git a/doc/manual/source/release-notes-determinate/rl-3.6.6.md b/doc/manual/source/release-notes-determinate/rl-3.6.6.md
new file mode 100644
index 000000000..55e903d7c
--- /dev/null
+++ b/doc/manual/source/release-notes-determinate/rl-3.6.6.md
@@ -0,0 +1,17 @@
+# Release 3.6.6 (2025-06-17)
+
+* Based on [upstream Nix 2.29.0](../release-notes/rl-2.29.md).
+
+## What's Changed
+* Release v3.6.4 by @github-actions in [DeterminateSystems/nix-src#109](https://github.com/DeterminateSystems/nix-src/pull/109)
+* Fixup the complainy docs line by @grahamc in [DeterminateSystems/nix-src#111](https://github.com/DeterminateSystems/nix-src/pull/111)
+* Move the actual vm tests / flake regressions into the generic build phase by @grahamc in [DeterminateSystems/nix-src#112](https://github.com/DeterminateSystems/nix-src/pull/112)
+* Fix broken fetchToStore() caching by @edolstra in [DeterminateSystems/nix-src#110](https://github.com/DeterminateSystems/nix-src/pull/110)
+* Parallelize the flake regression suite by @grahamc in [DeterminateSystems/nix-src#114](https://github.com/DeterminateSystems/nix-src/pull/114)
+* Don't build fallback-paths if we didn't build aarch64-linux and x86 d…   …arwin by @grahamc in [DeterminateSystems/nix-src#116](https://github.com/DeterminateSystems/nix-src/pull/116)
+* Use GHA runners for VMs since they have KVM by @grahamc in [DeterminateSystems/nix-src#118](https://github.com/DeterminateSystems/nix-src/pull/118)
+* fetchToStore() cache: Use content hashes instead of store paths by @edolstra in [DeterminateSystems/nix-src#115](https://github.com/DeterminateSystems/nix-src/pull/115)
+* Release v3.6.5 by @github-actions in [DeterminateSystems/nix-src#119](https://github.com/DeterminateSystems/nix-src/pull/119)
+
+
+**Full Changelog**: [v3.6.3...v3.6.6](https://github.com/DeterminateSystems/nix-src/compare/v3.6.3...v3.6.6)