diff --git a/.gitattributes b/.gitattributes
index b8693428..6d4ec2e7 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -15,6 +15,7 @@
 phpcs.xml.dist          export-ignore
 phpdoc.dist.xml         export-ignore
 phpdoc.xml.dist         export-ignore
+phpstan.neon.dist       export-ignore
 phpunit.xml.dist        export-ignore
 phpunit10.xml.dist      export-ignore
 /.github/               export-ignore
diff --git a/.github/workflows/basics.yml b/.github/workflows/basics.yml
index 9e58809f..266447bf 100644
--- a/.github/workflows/basics.yml
+++ b/.github/workflows/basics.yml
@@ -82,6 +82,33 @@ jobs:
         if: ${{ always() && steps.phpcs.outcome == 'failure' }}
         run: cs2pr ./phpcs-report.xml
 
+  phpstan:
+    name: "PHPStan"
+    runs-on: "ubuntu-latest"
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 'latest'
+          coverage: none
+          tools: phpstan
+
+      # Install dependencies and handle caching in one go.
+      # Dependencies need to be installed to make sure the PHPCS and PHPUnit classes are recognized.
+      # @link https://github.com/marketplace/actions/install-composer-dependencies
+      - name: Install Composer dependencies
+        uses: "ramsey/composer-install@v2"
+        with:
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
+
+      - name: Run PHPStan
+        run: phpstan analyse
+
   markdownlint:
     name: 'Lint Markdown'
     runs-on: ubuntu-latest
diff --git a/.gitignore b/.gitignore
index c88cda6f..20a89389 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@ vendor/
 /.phpunit.result.cache
 /docs/phpdoc/
 !/docs/phpdoc/.nojekyll
+phpstan.neon
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 00000000..027a3c88
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,95 @@
+parameters:
+    #phpVersion: 50400 # Needs to be 70100 or higher... sigh...
+    level: 6
+    paths:
+        - phpcsutils-autoload.php
+        - .github/GHPages
+        - PHPCSUtils
+        - Tests
+    excludePaths:
+        # This file needs to be excluded as the availability of the traits depends on which PHPUnit Polyfills version is loaded/installed.
+        - Tests/PolyfilledTestCase.php
+    bootstrapFiles:
+        - Tests/bootstrap.php
+    treatPhpDocTypesAsCertain: false
+
+    ignoreErrors:
+        # Level 0
+        # Ignoring this as availability depends on which PHPUnit Polyfills version is loaded/installed. This is 100% okay.
+        -
+            message: '`^Call to an undefined method \S+UtilityMethodTestCase::setExpectedException\(\)\.$`'
+            path: PHPCSUtils/TestUtils/UtilityMethodTestCase.php
+            count: 1
+
+        # Level 1
+        # These are on purpose for testing the magic method. This is 100% okay.
+        -
+            message: '`^Call to an undefined static method PHPCSUtils\\BackCompat\\BCTokens::notATokenArray\(\)\.$`'
+            path: Tests/BackCompat/BCTokens/UnchangedTokenArraysTest.php
+            count: 1
+        -
+            message: '`^Call to an undefined static method PHPCSUtils\\Tokens\\Collections::notATokenArray\(\)\.$`'
+            path: Tests/Tokens/Collections/PropertyBasedTokenArraysTest.php
+            count: 1
+
+        # Level 2
+        # Ignoring as this refers to a non-mocked method on the original class. This is 100% okay.
+        -
+            message: '`^Call to an undefined method PHPUnit\\Framework\\MockObject\\MockObject::process\(\)\.$`'
+            path: Tests/AbstractSniffs/AbstractArrayDeclaration/AbstractArrayDeclarationSniffTest.php
+        # Ignoring as availability depends on which PHPUnit version is loaded/installed. This is 100% okay.
+        -
+            message: '`^Call to an undefined method PHPUnit\\Framework\\MockObject\\MockBuilder<[^>]+>::setMethods\(\)\.$`'
+            path: Tests/AbstractSniffs/AbstractArrayDeclaration/AbstractArrayDeclarationSniffTest.php
+            count: 1
+
+        # Level 3
+        # Ignoring as `null` is the initial value for config settings in PHPCS which this test is resetting to.
+        # The PHPCS docs just don't reflect that. This is 100% okay.
+        -
+            message: '`^Property PHP_CodeSniffer\\Config::\$\S+ \([^\)]+\) does not accept null\.$`'
+            path: Tests/BackCompat/Helper/GetCommandLineDataTest.php
+
+        # Level 4
+        # This is by design.
+        -
+            message: '`^Static method PHPCSUtils\\Tokens\\Collections::triggerDeprecation\(\) is unused\.$`'
+            path: PHPCSUtils/Tokens/Collections.php
+            count: 1
+
+        # This depends on the PHP version on which PHPStan is being run, so not valid.
+        -
+            message: "`^Comparison operation \"\\>\\=\" between '[0-9\\. -]+' and 10 is always true\\.$`"
+            path: Tests/Utils/Orthography/FirstCharTest.php
+            count: 1
+        -
+            message: '`^Else branch is unreachable because previous condition is always true\.$`'
+            path: Tests/Utils/Orthography/FirstCharTest.php
+            count: 1
+
+        # Level 5
+        # This is by design to test handling of incorrect input.
+        -
+            message: '`^Parameter #[0-9]+ \$\S+ of static method PHPCSUtils\\(?!Tests)[A-Za-z]+\\[A-Za-z]+::[A-Za-z]+\(\) expects [^,]+, \S+ given\.$`'
+            paths:
+              - Tests/BackCompat/BCFile/GetTokensAsStringTest.php
+              - Tests/Exceptions/TestTargetNotFound/TestTargetNotFoundTest.php
+              - Tests/Fixers/SpacesFixer/SpacesFixerExceptionsTest.php
+              - Tests/Utils/GetTokensAsString/GetTokensAsStringTest.php
+
+        # Ignoring as this is fine.
+        -
+            message: '`^Parameter #1 \$exception of method PHPUnit\\Framework\\TestCase::expectException\(\) expects class-string<Throwable>, string given\.$`'
+            path: Tests/TestUtils/UtilityMethodTestCase/SkipJSCSSTestsOnPHPCS4Test.php
+            count: 1
+
+        # Level 6
+        # Test data providers.
+        -
+            message: '`^Method PHPCSUtils\\Tests\\[^: ]+Test(Case)?::data\S+\(\) return type has no value type specified in iterable type array\.$`'
+            path: Tests/*
+
+        # Test methods.
+        -
+            message: '`^Method PHPCSUtils\\Tests\\[^: ]+Test(Case)?::\S+\(\) has parameter \$\S* with no value type specified in iterable type array\.$`'
+            path: Tests/*