diff --git a/CHANGELOG.md b/CHANGELOG.md
index 13a3f60..8172540 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.5.1] - 2026-08-15
+
+### Fixed
+- Corrected the segment condition documentation on `SegmentConditionGroup`: conditions **within a group** are joined by `OR`, and **groups** are joined by `AND` — i.e. `(A OR B) AND (C OR D)`. The previous docstring stated the inverse. No behaviour change — the API has always evaluated segments this way, and no code paths were touched. Worth a read if you built a segment against the old description, since it may target a wider or narrower audience than you intended.
+
 ## [1.5.0] - 2026-08-14
 
 Covers the reworked bulk contact import (TPL-2105) and the duplicate-create fix.
@@ -283,7 +288,8 @@ the exact same payloads.
   `ValidationError`, `NotFoundError`, `ConflictError`, `BadRequestError`,
   `ServerError`)
 
-[Unreleased]: https://github.com/lettr/lettr-python/compare/v1.4.0...HEAD
+[Unreleased]: https://github.com/lettr/lettr-python/compare/v1.5.1...HEAD
+[1.5.1]: https://github.com/lettr/lettr-python/compare/v1.5.0...v1.5.1
 [1.5.0]: https://github.com/lettr/lettr-python/compare/v1.4.0...v1.5.0
 [1.4.0]: https://github.com/lettr/lettr-python/compare/v1.3.0...v1.4.0
 [1.3.0]: https://github.com/lettr/lettr-python/compare/v1.2.0...v1.3.0
diff --git a/pyproject.toml b/pyproject.toml
index 7ece0d0..4eec0f4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "lettr"
-version = "1.5.0"
+version = "1.5.1"
 description = "Official Python SDK for the Lettr Email API"
 readme = "README.md"
 license = "MIT"
diff --git a/src/lettr/_types.py b/src/lettr/_types.py
index 127ea14..076914b 100644
--- a/src/lettr/_types.py
+++ b/src/lettr/_types.py
@@ -610,7 +610,8 @@ class AudienceSegment:
     """An audience segment.
 
     ``condition_groups`` is kept as a list of raw dicts mirroring the
-    API shape (groups joined by OR, conditions within a group joined by AND).
+    API shape (conditions within a group joined by OR, groups joined by
+    AND) -- i.e. (A OR B) AND (C OR D).
     """
 
     id: str