diff --git a/app/src/App/API.purs b/app/src/App/API.purs
index afabd0bc..7fb542ba 100644
--- a/app/src/App/API.purs
+++ b/app/src/App/API.purs
@@ -2,6 +2,7 @@ module Registry.App.API
   ( AuthenticatedEffects
   , COMPILER_CACHE
   , CompilerCache(..)
+  , LicenseValidationError(..)
   , PackageSetUpdateEffects
   , PublishEffects
   , _compilerCache
@@ -12,8 +13,10 @@ module Registry.App.API
   , getPacchettiBotti
   , packageSetUpdate
   , packagingTeam
+  , printLicenseValidationError
   , publish
   , removeIgnoredTarballFiles
+  , validateLicense
   ) where
 
 import Registry.App.Prelude
@@ -53,6 +56,7 @@ import Parsing.Combinators.Array as Parsing.Combinators.Array
 import Parsing.String as Parsing.String
 import Registry.API.V1 (PackageSetJobData)
 import Registry.App.Auth as Auth
+import Registry.App.CLI.Licensee as Licensee
 import Registry.App.CLI.Purs (CompilerFailure(..), compilerFailureCodec)
 import Registry.App.CLI.Purs as Purs
 import Registry.App.CLI.PursVersions as PursVersions
@@ -90,6 +94,7 @@ import Registry.Foreign.Octokit (Team)
 import Registry.Foreign.Tmp as Tmp
 import Registry.Internal.Codec as Internal.Codec
 import Registry.Internal.Path as Internal.Path
+import Registry.License as License
 import Registry.Location as Location
 import Registry.Manifest as Manifest
 import Registry.Metadata as Metadata
@@ -519,6 +524,11 @@ publish maybeLegacyIndex payload = do
   when (Operation.Validation.isMetadataPackage (Manifest receivedManifest)) do
     Except.throw "The `metadata` package cannot be uploaded to the registry because it is a protected package."
 
+  Log.info "Verifying licenses are consistent among manifest files..."
+  validateLicense downloadedPackage receivedManifest.license >>= case _ of
+    Nothing -> Log.debug "License validation passed."
+    Just err -> Except.throw $ printLicenseValidationError err
+
   for_ (Operation.Validation.isNotUnpublished (Manifest receivedManifest) (Metadata metadata)) \info -> do
     Except.throw $ String.joinWith "\n"
       [ "You tried to upload a version that has been unpublished: " <> Version.print receivedManifest.version
@@ -1322,3 +1332,82 @@ instance FsEncodable CompilerCache where
           }
 
       Exists.mkExists $ Cache.AsJson cacheKey codec next
+
+-- | Errors that can occur when validating license consistency
+data LicenseValidationError = LicenseMismatch
+  { manifestLicense :: License
+  , detectedLicenses :: Array License
+  }
+
+derive instance Eq LicenseValidationError
+
+printLicenseValidationError :: LicenseValidationError -> String
+printLicenseValidationError = case _ of
+  LicenseMismatch { manifestLicense, detectedLicenses } -> Array.fold
+    [ "License mismatch: The manifest specifies license '"
+    , License.print manifestLicense
+    , "' but the following license(s) were detected in your repository: "
+    , String.joinWith ", " (map License.print detectedLicenses)
+    , ". Please ensure your manifest license accurately represents all licenses "
+    , "in your repository. If multiple licenses apply, join them using SPDX "
+    , "conjunctions (e.g., 'MIT AND Apache-2.0' or 'MIT OR Apache-2.0')."
+    ]
+
+-- | Validate that the license in the manifest is consistent with licenses
+-- | detected in the repository (LICENSE file, package.json, bower.json).
+-- |
+-- | This check ensures that the SPDX identifier asserted in the package
+-- | manifest accurately represents the licenses present in the repository.
+-- | If multiple distinct licenses are detected, they must all be represented
+-- | in the manifest license (e.g., joined with AND or OR).
+validateLicense :: forall r. FilePath -> License -> Run (LOG + AFF + r) (Maybe LicenseValidationError)
+validateLicense packageDir manifestLicense = do
+  Log.debug "Detecting licenses from repository files..."
+  detected <- Run.liftAff $ Licensee.detect packageDir
+  case detected of
+    Left err -> do
+      Log.warn $ "License detection failed, relying on manifest: " <> err
+      pure Nothing
+    Right detectedStrings -> do
+      let
+        parsedLicenses :: Array License
+        parsedLicenses = Array.mapMaybe (hush <<< License.parse) detectedStrings
+
+      Log.debug $ "Detected licenses: " <> String.joinWith ", " detectedStrings
+
+      if Array.null parsedLicenses then do
+        Log.debug "No licenses detected from repository files, nothing to validate."
+        pure Nothing
+      else case License.extractIds manifestLicense of
+        Left err -> do
+          -- This shouldn't be possible (we have already validated the license)
+          -- as part of constructing the manifest
+          Log.warn $ "Could not extract license IDs from manifest: " <> err
+          pure Nothing
+        Right manifestIds -> do
+          let
+            manifestIdSet = Set.fromFoldable manifestIds
+
+            -- A detected license is covered if all its IDs are in the manifest IDs
+            isCovered :: License -> Boolean
+            isCovered license = case License.extractIds license of
+              Left _ -> false
+              Right ids -> Array.all (\id -> Set.member id manifestIdSet) ids
+
+            uncoveredLicenses :: Array License
+            uncoveredLicenses = Array.filter (not <<< isCovered) parsedLicenses
+
+          if Array.null uncoveredLicenses then do
+            Log.debug "All detected licenses are covered by the manifest license."
+            pure Nothing
+          else do
+            Log.warn $ Array.fold
+              [ "License mismatch detected: manifest has '"
+              , License.print manifestLicense
+              , "' but detected "
+              , String.joinWith ", " (map License.print parsedLicenses)
+              ]
+            pure $ Just $ LicenseMismatch
+              { manifestLicense
+              , detectedLicenses: uncoveredLicenses
+              }
diff --git a/app/test/App/API.purs b/app/test/App/API.purs
index 28f17f90..36d9a488 100644
--- a/app/test/App/API.purs
+++ b/app/test/App/API.purs
@@ -14,6 +14,7 @@ import Effect.Ref as Ref
 import Node.FS.Aff as FS.Aff
 import Node.Path as Path
 import Node.Process as Process
+import Registry.App.API (LicenseValidationError(..), validateLicense)
 import Registry.App.API as API
 import Registry.App.CLI.Tar as Tar
 import Registry.App.Effect.Env as Env
@@ -27,6 +28,7 @@ import Registry.Foreign.FSExtra as FS.Extra
 import Registry.Foreign.FastGlob as FastGlob
 import Registry.Foreign.Tmp as Tmp
 import Registry.Internal.Codec as Internal.Codec
+import Registry.License as License
 import Registry.Manifest as Manifest
 import Registry.ManifestIndex as ManifestIndex
 import Registry.PackageName as PackageName
@@ -57,6 +59,9 @@ spec = do
   Spec.describe "Verifies build plans" do
     checkBuildPlanToResolutions
 
+  Spec.describe "Validates licenses match" do
+    licenseValidation
+
   Spec.describe "Includes correct files in tarballs" do
     removeIgnoredTarballFiles
     copySourceFiles
@@ -441,3 +446,47 @@ copySourceFiles = Spec.hoistSpec identity (\_ -> Assert.Run.runBaseEffects) $ Sp
       writeFiles = Run.liftAff <<< traverse_ (\path -> FS.Aff.writeTextFile UTF8 (inTmp path) "module Module where")
 
     pure { source: tmp, destination: destTmp, writeDirectories, writeFiles }
+
+licenseValidation :: Spec.Spec Unit
+licenseValidation = do
+  let fixtures = Path.concat [ "app", "fixtures", "licenses", "halogen-hooks" ]
+
+  Spec.describe "validateLicense" do
+    Spec.it "Passes when manifest license covers all detected licenses" do
+      -- The halogen-hooks fixture has MIT in LICENSE and Apache-2.0 in package.json
+      let manifestLicense = unsafeLicense "MIT AND Apache-2.0"
+      result <- Assert.Run.runBaseEffects $ validateLicense fixtures manifestLicense
+      Assert.shouldEqual Nothing result
+
+    Spec.it "Fails when manifest license does not cover a detected license" do
+      -- Manifest says MIT only, but Apache-2.0 is also in package.json
+      let manifestLicense = unsafeLicense "MIT"
+      result <- Assert.Run.runBaseEffects $ validateLicense fixtures manifestLicense
+      case result of
+        Just (LicenseMismatch { detectedLicenses }) ->
+          -- Should detect that Apache-2.0 is not covered
+          Assert.shouldContain (map License.print detectedLicenses) "Apache-2.0"
+        _ ->
+          Assert.fail "Expected LicenseMismatch error"
+
+    Spec.it "Fails when manifest has completely different license" do
+      -- Manifest says BSD-3-Clause, but fixture has MIT and Apache-2.0
+      let manifestLicense = unsafeLicense "BSD-3-Clause"
+      result <- Assert.Run.runBaseEffects $ validateLicense fixtures manifestLicense
+      case result of
+        Just (LicenseMismatch { manifestLicense: ml, detectedLicenses }) -> do
+          Assert.shouldEqual "BSD-3-Clause" (License.print ml)
+          -- Both MIT and Apache-2.0 should be in the detected licenses
+          Assert.shouldContain (map License.print detectedLicenses) "MIT"
+          Assert.shouldContain (map License.print detectedLicenses) "Apache-2.0"
+        _ ->
+          Assert.fail "Expected LicenseMismatch error"
+
+    Spec.it "Passes when manifest uses OR conjunction" do
+      -- OR conjunction is also valid - means either license applies
+      let manifestLicense = unsafeLicense "MIT OR Apache-2.0"
+      result <- Assert.Run.runBaseEffects $ validateLicense fixtures manifestLicense
+      Assert.shouldEqual Nothing result
+
+unsafeLicense :: String -> License
+unsafeLicense str = unsafeFromRight $ License.parse str
diff --git a/lib/src/License.js b/lib/src/License.js
index 451fc774..1faaccfe 100644
--- a/lib/src/License.js
+++ b/lib/src/License.js
@@ -8,3 +8,34 @@ export const parseSPDXLicenseIdImpl = (onError, onSuccess, identifier) => {
     return onError(`Invalid SPDX identifier ${identifier}`);
   }
 };
+
+// Extract all license IDs from a parsed SPDX expression AST.
+// The AST structure from spdx-expression-parse is:
+// - Simple: { license: 'MIT' }
+// - With exception: { license: 'GPL-2.0', exception: 'Classpath-exception-2.0' }
+// - Compound: { left: {...}, conjunction: 'and'|'or', right: {...} }
+const extractLicenseIds = (ast) => {
+  const ids = new Set();
+
+  const walk = (node) => {
+    if (!node) return;
+    if (node.license) {
+      // Normalize to uppercase for case-insensitive comparison
+      ids.add(node.license.toUpperCase());
+    }
+    if (node.left) walk(node.left);
+    if (node.right) walk(node.right);
+  };
+
+  walk(ast);
+  return Array.from(ids);
+};
+
+export const extractLicenseIdsImpl = (onError, onSuccess, expression) => {
+  try {
+    const ast = parse(expression);
+    return onSuccess(extractLicenseIds(ast));
+  } catch (_) {
+    return onError(`Invalid SPDX expression: ${expression}`);
+  }
+};
diff --git a/lib/src/License.purs b/lib/src/License.purs
index fa5ab972..8e8d1678 100644
--- a/lib/src/License.purs
+++ b/lib/src/License.purs
@@ -9,6 +9,7 @@ module Registry.License
   ( License
   , SPDXConjunction(..)
   , codec
+  , extractIds
   , joinWith
   , parse
   , print
@@ -52,6 +53,14 @@ foreign import parseSPDXLicenseIdImpl :: forall r. Fn3 (String -> r) (String ->
 parse :: String -> Either String License
 parse = runFn3 parseSPDXLicenseIdImpl Left (Right <<< License)
 
+foreign import extractLicenseIdsImpl :: forall r. Fn3 (String -> r) (Array String -> r) String r
+
+-- | Extract all license identifiers from a SPDX expression.
+-- | Returns an array of uppercase license IDs for case-insensitive comparison.
+-- | For example, "MIT AND Apache-2.0" returns ["MIT", "APACHE-2.0"].
+extractIds :: License -> Either String (Array String)
+extractIds (License expr) = runFn3 extractLicenseIdsImpl Left Right expr
+
 -- | A valid conjunction for SPDX license identifiers. AND means that both
 -- | licenses must be satisfied; OR means that at least one license must be
 -- | satisfied.
diff --git a/lib/test/Registry/License.purs b/lib/test/Registry/License.purs
index d2a6a7cd..41e914a8 100644
--- a/lib/test/Registry/License.purs
+++ b/lib/test/Registry/License.purs
@@ -44,6 +44,49 @@ spec = do
       Left err -> Assert.fail $ "joinWith created unparseable expression: " <> License.print joined <> " - Error: " <> err
       Right _ -> pure unit
 
+  Spec.describe "extractIds" do
+    Spec.it "extracts single license ID" do
+      case License.parse "MIT" of
+        Left err -> Assert.fail err
+        Right license -> case License.extractIds license of
+          Left err -> Assert.fail err
+          Right ids -> Assert.shouldEqual [ "MIT" ] ids
+
+    Spec.it "extracts IDs from AND expression" do
+      case License.parse "MIT AND Apache-2.0" of
+        Left err -> Assert.fail err
+        Right license -> case License.extractIds license of
+          Left err -> Assert.fail err
+          Right ids -> do
+            Assert.shouldContain ids "MIT"
+            Assert.shouldContain ids "APACHE-2.0"
+
+    Spec.it "extracts IDs from OR expression" do
+      case License.parse "MIT OR BSD-3-Clause" of
+        Left err -> Assert.fail err
+        Right license -> case License.extractIds license of
+          Left err -> Assert.fail err
+          Right ids -> do
+            Assert.shouldContain ids "MIT"
+            Assert.shouldContain ids "BSD-3-CLAUSE"
+
+    Spec.it "extracts IDs from nested expression" do
+      case License.parse "MIT AND (Apache-2.0 OR BSD-3-Clause)" of
+        Left err -> Assert.fail err
+        Right license -> case License.extractIds license of
+          Left err -> Assert.fail err
+          Right ids -> do
+            Assert.shouldContain ids "MIT"
+            Assert.shouldContain ids "APACHE-2.0"
+            Assert.shouldContain ids "BSD-3-CLAUSE"
+
+    Spec.it "normalizes license IDs to uppercase" do
+      case License.parse "mit" of
+        Left err -> Assert.fail err
+        Right license -> case License.extractIds license of
+          Left err -> Assert.fail err
+          Right ids -> Assert.shouldEqual [ "MIT" ] ids
+
 valid :: Array String
 valid =
   [ "MIT"