diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index a77b1c5f..b086d751 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -164,6 +164,30 @@ jobs:
             PYTHON_VERSION: "3.11"
             CC_OUTER_LOOP: "gcc"
             CC_INNER_LOOP: "clang-18"
+          # Linux + conda-forge Python RC, extra deps from PyPI.
+          # OpenCV is omitted: no wheels for the current RC ABI yet.
+          - name: pyrc_pip
+            os: ubuntu-latest
+            PACKAGER: "pip"
+            # Using the "*" marker does not select the latest RC release
+            # from the conda-forge `python_rc` channel hence the need to pin
+            # a specific Python version when testing against an RC release.
+            PYTHON_VERSION: "3.15"
+            PYTHON_RC: "true"
+            CC_OUTER_LOOP: "gcc"
+            CC_INNER_LOOP: "gcc"
+          # Linux + conda-forge free-threaded Python RC, extra deps from PyPI.
+          - name: pyrc_ft_pip
+            os: ubuntu-latest
+            PACKAGER: "pip"
+            # Using the "*" marker does not select the latest RC release
+            # from the conda-forge `python_rc` channel hence the need to pin
+            # a specific Python version when testing against an RC release.
+            PYTHON_VERSION: "3.15"
+            PYTHON_RC: "true"
+            FREETHREADING: "1"
+            CC_OUTER_LOOP: "gcc"
+            CC_INNER_LOOP: "gcc"
           # Linux environment with numpy from conda-forge channel and openblas-openmp
           - name: pylatest_conda_forge
             os: ubuntu-latest
diff --git a/CHANGES.md b/CHANGES.md
index 2529e3bc..d7a4bb27 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,9 @@
   quite a bit of overhead.
   https://github.com/joblib/threadpoolctl/pull/250
 
+- Added official support for Python 3.15, and declared support for Python 3.14
+  in package metadata.
+  https://github.com/joblib/threadpoolctl/issues/251
 
 3.7.0 (2026-09-15)
 ==================
diff --git a/continuous_integration/install.sh b/continuous_integration/install.sh
index 42c551ba..01190bdb 100755
--- a/continuous_integration/install.sh
+++ b/continuous_integration/install.sh
@@ -43,7 +43,7 @@ make_conda() {
 
     if [[ "$FREETHREADING" == "1" ]]; then
         TO_INSTALL="$TO_INSTALL python-freethreading"
-    elif [[ "$PYTHON_VERSION" == "*" ]]; then
+    elif [[ "$PYTHON_VERSION" == "*" || "$PYTHON_RC" == "true" ]]; then
         # Avoid installing free-threaded python
         TO_INSTALL="$TO_INSTALL python-gil"
     fi
@@ -53,6 +53,12 @@ make_conda() {
     # prevent mixing conda channels
     conda config --set channel_priority strict
     conda config --add channels $CHANNEL
+    if [[ "$PYTHON_RC" == "true" ]]; then
+        # Python RC builds are on conda-forge main but depend on _python_rc,
+        # which is only published on this label. Keep the label at lower
+        # priority than conda-forge so the interpreter still comes from main.
+        conda config --append channels conda-forge/label/python_rc
+    fi
 
     conda update -n base conda conda-libmamba-solver -q --yes
     conda config --set solver libmamba
@@ -134,6 +140,7 @@ if [[ "$UNAMESTR" == "Linux" && "$NO_NUMPY" != "true" ]]; then
 fi
 
 python --version
+python -c "import sys, sysconfig; print('Py_GIL_DISABLED', sysconfig.get_config_var('Py_GIL_DISABLED')); print('sys._is_gil_enabled', getattr(sys, '_is_gil_enabled', lambda: 'n/a')())"
 python -c "import numpy; print(f'numpy {numpy.__version__}')" || echo "no numpy"
 python -c "import scipy; print(f'scipy {scipy.__version__}')" || echo "no scipy"
 
diff --git a/continuous_integration/run_tests.sh b/continuous_integration/run_tests.sh
index 97814b8d..6b127711 100755
--- a/continuous_integration/run_tests.sh
+++ b/continuous_integration/run_tests.sh
@@ -16,10 +16,20 @@ elif [[ "$PACKAGER" == "ubuntu" ]]; then
     pip list
 fi
 
+if [[ "$FREETHREADING" == "1" ]]; then
+    python -c "import sys; assert hasattr(sys, '_is_gil_enabled') and not sys._is_gil_enabled(), 'expected a free-threaded interpreter with the GIL disabled'"
+elif [[ "$PYTHON_RC" == "true" ]]; then
+    python -c "import sys, sysconfig; assert sysconfig.get_config_var('Py_GIL_DISABLED') in (0, None) and sys._is_gil_enabled(), 'expected a GIL-enabled Python RC'"
+fi
+
 # Use the CLI to display the effective runtime environment prior to
 # launching the tests:
 python -m threadpoolctl -i numpy scipy.linalg tests._openmp_test_helper.openmp_helpers_inner
 
+if [[ "$FREETHREADING" == "1" ]]; then
+    python -c "import sys, numpy, scipy.linalg, tests._openmp_test_helper.openmp_helpers_inner as _; assert not sys._is_gil_enabled(), 'GIL was re-enabled after importing native extensions'"
+fi
+
 # Introspect API scope:
 PYTHONPATH=. python -X faulthandler tests/empirical_scope_observation.py blas
 PYTHONPATH=. python -X faulthandler tests/empirical_scope_observation.py openmp
diff --git a/pyproject.toml b/pyproject.toml
index e2a35c6a..f2ff8a65 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,6 +17,8 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: 3.15",
     "Topic :: Software Development :: Libraries :: Python Modules",
 ]