diff --git a/action.yml b/action.yml
index 3a6531c88..8b3326659 100644
--- a/action.yml
+++ b/action.yml
@@ -29,6 +29,8 @@ inputs:
 outputs:
   python-version:
     description: "The installed Python or PyPy version. Useful when given a version range as input."
+  python-versions:
+    description: "A comma-separated list of all installed Python implementations and versions. Useful for cache-busting."
   cache-hit:
     description: "A boolean value to indicate a cache entry was found"
   python-path:
diff --git a/dist/setup/index.js b/dist/setup/index.js
index 4f9ca50c6..ef6ff23fd 100644
--- a/dist/setup/index.js
+++ b/dist/setup/index.js
@@ -70208,6 +70208,7 @@ function run() {
             const allowPreReleases = core.getBooleanInput('allow-prereleases');
             if (versions.length) {
                 let pythonVersion = '';
+                const pythonVersions = [];
                 const arch = core.getInput('architecture') || os.arch();
                 const updateEnvironment = core.getBooleanInput('update-environment');
                 core.startGroup('Installed versions');
@@ -70215,11 +70216,13 @@ function run() {
                     if (isPyPyVersion(version)) {
                         const installed = yield finderPyPy.findPyPyVersion(version, arch, updateEnvironment, checkLatest, allowPreReleases);
                         pythonVersion = `${installed.resolvedPyPyVersion}-${installed.resolvedPythonVersion}`;
+                        pythonVersions.push(`${installed.resolvedPythonVersion}-pypy${installed.resolvedPyPyVersion}`);
                         core.info(`Successfully set up PyPy ${installed.resolvedPyPyVersion} with Python (${installed.resolvedPythonVersion})`);
                     }
                     else if (isGraalPyVersion(version)) {
                         const installed = yield finderGraalPy.findGraalPyVersion(version, arch, updateEnvironment, checkLatest, allowPreReleases);
                         pythonVersion = `${installed}`;
+                        pythonVersions.push(`graalpy${installed}`);
                         core.info(`Successfully set up GraalPy ${installed}`);
                     }
                     else {
@@ -70228,9 +70231,11 @@ function run() {
                         }
                         const installed = yield finder.useCpythonVersion(version, arch, updateEnvironment, checkLatest, allowPreReleases);
                         pythonVersion = installed.version;
+                        pythonVersions.push(installed.version);
                         core.info(`Successfully set up ${installed.impl} (${pythonVersion})`);
                     }
                 }
+                core.setOutput('python-versions', pythonVersions.sort().join(','));
                 core.endGroup();
                 const cache = core.getInput('cache');
                 if (cache && utils_1.isCacheFeatureAvailable()) {
diff --git a/src/setup-python.ts b/src/setup-python.ts
index 05db90cbc..7a99ddd55 100644
--- a/src/setup-python.ts
+++ b/src/setup-python.ts
@@ -95,6 +95,7 @@ async function run() {
 
     if (versions.length) {
       let pythonVersion = '';
+      const pythonVersions: string[] = [];
       const arch: string = core.getInput('architecture') || os.arch();
       const updateEnvironment = core.getBooleanInput('update-environment');
       core.startGroup('Installed versions');
@@ -108,6 +109,9 @@ async function run() {
             allowPreReleases
           );
           pythonVersion = `${installed.resolvedPyPyVersion}-${installed.resolvedPythonVersion}`;
+          pythonVersions.push(
+            `${installed.resolvedPythonVersion}-pypy${installed.resolvedPyPyVersion}`
+          );
           core.info(
             `Successfully set up PyPy ${installed.resolvedPyPyVersion} with Python (${installed.resolvedPythonVersion})`
           );
@@ -120,6 +124,7 @@ async function run() {
             allowPreReleases
           );
           pythonVersion = `${installed}`;
+          pythonVersions.push(`graalpy${installed}`);
           core.info(`Successfully set up GraalPy ${installed}`);
         } else {
           if (version.startsWith('2')) {
@@ -135,9 +140,11 @@ async function run() {
             allowPreReleases
           );
           pythonVersion = installed.version;
+          pythonVersions.push(installed.version);
           core.info(`Successfully set up ${installed.impl} (${pythonVersion})`);
         }
       }
+      core.setOutput('python-versions', pythonVersions.sort().join(','));
       core.endGroup();
       const cache = core.getInput('cache');
       if (cache && isCacheFeatureAvailable()) {

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