diff --git a/src/CLI/TargetPhpVersion.php b/src/CLI/TargetPhpVersion.php
index 1da49ab5..09a1bb39 100644
--- a/src/CLI/TargetPhpVersion.php
+++ b/src/CLI/TargetPhpVersion.php
@@ -25,7 +25,12 @@ private function __construct(?string $version)
         $this->version = $version;
     }
 
-    public static function create(?string $version): self
+    /**
+     * @param ?string $version
+     *
+     * @throws PhpVersionNotValidException
+     */
+    public static function create(?string $version = null): self
     {
         if (null === $version) {
             return new self(phpversion());
diff --git a/src/Expression/NegateDecorator.php b/src/Expression/NegateDecorator.php
new file mode 100644
index 00000000..ce7a5774
--- /dev/null
+++ b/src/Expression/NegateDecorator.php
@@ -0,0 +1,57 @@
+<?php
+declare(strict_types=1);
+
+namespace Arkitect\Expression;
+
+use Arkitect\Analyzer\ClassDescription;
+use Arkitect\Rules\Violation;
+use Arkitect\Rules\ViolationMessage;
+use Arkitect\Rules\Violations;
+
+class NegateDecorator implements Expression
+{
+    /** @var Expression */
+    private $expression;
+
+    public function __construct(Expression $expression)
+    {
+        $this->expression = $expression;
+    }
+
+    public function describe(ClassDescription $theClass, string $because): Description
+    {
+        $description = $this->expression->describe($theClass, $because)->toString();
+
+        $description = str_replace(
+            ['should not'],
+            ['should'],
+            $description,
+            $count
+        );
+
+        if (0 === $count) {
+            $description = str_replace(
+                ['should'],
+                ['should not'],
+                $description,
+                $count
+            );
+        }
+
+        return new Description($description, '');
+    }
+
+    public function evaluate(ClassDescription $theClass, Violations $violations, string $because): void
+    {
+        $this->expression->evaluate($theClass, $currentViolations = new Violations(), $because);
+
+        if (0 === $currentViolations->count()) {
+            $violations->add(
+                Violation::create(
+                    $theClass->getFQCN(),
+                    ViolationMessage::selfExplanatory($this->describe($theClass, $because))
+                )
+            );
+        }
+    }
+}
diff --git a/src/Rules/NoClass.php b/src/Rules/NoClass.php
new file mode 100644
index 00000000..3c2bc180
--- /dev/null
+++ b/src/Rules/NoClass.php
@@ -0,0 +1,42 @@
+<?php
+declare(strict_types=1);
+
+namespace Arkitect\Rules;
+
+use Arkitect\Expression\Expression;
+use Arkitect\Expression\NegateDecorator;
+use Arkitect\Rules\DSL\AndThatShouldParser;
+use Arkitect\Rules\DSL\BecauseParser;
+use Arkitect\Rules\DSL\ThatParser;
+
+class NoClass implements ThatParser
+{
+    /** @var RuleBuilder */
+    protected $ruleBuilder;
+
+    public function __construct()
+    {
+        $this->ruleBuilder = (new RuleBuilder())->negateShoulds();
+    }
+
+    public function should(Expression $expression): BecauseParser
+    {
+        $this->ruleBuilder->addShould(new NegateDecorator($expression));
+
+        return new Because($this->ruleBuilder);
+    }
+
+    public function that(Expression $expression): AndThatShouldParser
+    {
+        $this->ruleBuilder->addThat($expression);
+
+        return new AndThatShould($this->ruleBuilder);
+    }
+
+    public function except(string ...$classesToBeExcluded): ThatParser
+    {
+        $this->ruleBuilder->classesToBeExcluded(...$classesToBeExcluded);
+
+        return $this;
+    }
+}
diff --git a/src/Rules/Rule.php b/src/Rules/Rule.php
index 6562da7e..7908aa9f 100644
--- a/src/Rules/Rule.php
+++ b/src/Rules/Rule.php
@@ -9,4 +9,9 @@ public static function allClasses(): AllClasses
     {
         return new AllClasses();
     }
+
+    public static function noClass(): NoClass
+    {
+        return new NoClass();
+    }
 }
diff --git a/src/Rules/RuleBuilder.php b/src/Rules/RuleBuilder.php
index e6f12bf2..d8e2eca1 100644
--- a/src/Rules/RuleBuilder.php
+++ b/src/Rules/RuleBuilder.php
@@ -4,6 +4,7 @@
 namespace Arkitect\Rules;
 
 use Arkitect\Expression\Expression;
+use Arkitect\Expression\NegateDecorator;
 
 class RuleBuilder
 {
@@ -18,9 +19,13 @@ class RuleBuilder
 
     /** @var array */
     private $classesToBeExcluded;
+
     /** @var bool */
     private $runOnlyThis;
 
+    /** @var bool */
+    private $negateShoulds;
+
     public function __construct()
     {
         $this->thats = new Specs();
@@ -28,6 +33,7 @@ public function __construct()
         $this->because = '';
         $this->classesToBeExcluded = [];
         $this->runOnlyThis = false;
+        $this->negateShoulds = false;
     }
 
     public function addThat(Expression $that): self
@@ -39,6 +45,10 @@ public function addThat(Expression $that): self
 
     public function addShould(Expression $should): self
     {
+        if ($this->negateShoulds) {
+            $should = new NegateDecorator($should);
+        }
+
         $this->shoulds->add($should);
 
         return $this;
@@ -69,9 +79,9 @@ public function classesToBeExcluded(string ...$classesToBeExcluded): self
         return $this;
     }
 
-    public function setRunOnlyThis(): self
+    public function negateShoulds(): self
     {
-        $this->runOnlyThis = true;
+        $this->negateShoulds = true;
 
         return $this;
     }
diff --git a/src/Rules/Specs.php b/src/Rules/Specs.php
index c131d78f..ccb40006 100644
--- a/src/Rules/Specs.php
+++ b/src/Rules/Specs.php
@@ -8,7 +8,7 @@
 
 class Specs
 {
-    /** @var array */
+    /** @var list<Expression> */
     private $expressions = [];
 
     public function add(Expression $expression): void
@@ -18,7 +18,6 @@ public function add(Expression $expression): void
 
     public function allSpecsAreMatchedBy(ClassDescription $classDescription, string $because): bool
     {
-        /** @var Expression $spec */
         foreach ($this->expressions as $spec) {
             $violations = new Violations();
             $spec->evaluate($classDescription, $violations, $because);
diff --git a/tests/Expression/NegateDecoratorTest.php b/tests/Expression/NegateDecoratorTest.php
new file mode 100644
index 00000000..cab22b2c
--- /dev/null
+++ b/tests/Expression/NegateDecoratorTest.php
@@ -0,0 +1,56 @@
+<?php
+declare(strict_types=1);
+
+namespace Arkitect\Tests\Expression;
+
+use Arkitect\Analyzer\ClassDescription;
+use Arkitect\Expression\ForClasses\IsFinal;
+use Arkitect\Expression\ForClasses\IsNotFinal;
+use Arkitect\Expression\NegateDecorator;
+use Arkitect\Rules\Violations;
+use PHPUnit\Framework\TestCase;
+
+class NegateDecoratorTest extends TestCase
+{
+    public function test_positive_decoration(): void
+    {
+        $finalClass = ClassDescription::build('Tests\FinalClass')
+            ->setFinal(true)
+            ->get();
+
+        $isFinal = new IsFinal();
+
+        $isFinal->evaluate($finalClass, $violations = new Violations(), 'of some reason');
+        self::assertEquals('FinalClass should be final because of some reason', $isFinal->describe($finalClass, 'of some reason')->toString());
+
+        self::assertEquals(0, $violations->count());
+
+        $isNotFinal = new NegateDecorator($isFinal);
+
+        $isNotFinal->evaluate($finalClass, $violations = new Violations(), 'of some reason');
+        self::assertEquals('FinalClass should not be final because of some reason', $isNotFinal->describe($finalClass, 'of some reason')->toString());
+
+        self::assertEquals(1, $violations->count());
+    }
+
+    public function test_negative_decoration(): void
+    {
+        $finalClass = ClassDescription::build('Tests\FinalClass')
+            ->setFinal(true)
+            ->get();
+
+        $isNotFinal = new IsNotFinal();
+
+        $isNotFinal->evaluate($finalClass, $violations = new Violations(), '');
+
+        self::assertEquals(1, $violations->count());
+        self::assertEquals('FinalClass should not be final because of some reason', $isNotFinal->describe($finalClass, 'of some reason')->toString());
+
+        $isFinal = new NegateDecorator($isNotFinal);
+
+        $isFinal->evaluate($finalClass, $violations = new Violations(), '');
+
+        self::assertEquals(0, $violations->count());
+        self::assertEquals('FinalClass should be final because of some reason', $isFinal->describe($finalClass, 'of some reason')->toString());
+    }
+}
diff --git a/tests/Unit/Rules/NoClassRulesTest.php b/tests/Unit/Rules/NoClassRulesTest.php
new file mode 100644
index 00000000..8dc2b742
--- /dev/null
+++ b/tests/Unit/Rules/NoClassRulesTest.php
@@ -0,0 +1,64 @@
+<?php
+declare(strict_types=1);
+
+namespace Arkitect\Tests\Unit\Rules;
+
+use Arkitect\Analyzer\FileParserFactory;
+use Arkitect\ClassSet;
+use Arkitect\ClassSetRules;
+use Arkitect\CLI\Progress\VoidProgress;
+use Arkitect\CLI\Runner;
+use Arkitect\CLI\TargetPhpVersion;
+use Arkitect\Expression\ForClasses\HaveNameMatching;
+use Arkitect\Expression\ForClasses\NotResideInTheseNamespaces;
+use Arkitect\Expression\ForClasses\ResideInOneOfTheseNamespaces;
+use Arkitect\Rules\ParsingErrors;
+use Arkitect\Rules\Rule;
+use Arkitect\Rules\Violations;
+use PHPUnit\Framework\TestCase;
+
+class NoClassRulesTest extends TestCase
+{
+    public function test_no_class_without_that_clause_dsl_works(): void
+    {
+        $rule = Rule::noClass()
+            ->should(new NotResideInTheseNamespaces('App\Services'))
+            ->because('this namespace has been deprecated in favor of the modular architecture');
+
+        $classSet = ClassSet::fromDir(__DIR__.'/../../E2E/_fixtures/mvc');
+
+        $runner = new Runner();
+
+        $runner->check(
+            ClassSetRules::create($classSet, $rule),
+            new VoidProgress(),
+            FileParserFactory::createFileParser(TargetPhpVersion::create()),
+            $violations = new Violations(),
+            new ParsingErrors()
+        );
+
+        self::assertNotEmpty($violations->toArray());
+    }
+
+    public function test_no_class_dsl_works(): void
+    {
+        $rule = Rule::noClass()
+            ->that(new ResideInOneOfTheseNamespaces('App\Entity'))
+            ->should(new HaveNameMatching('*Service'))
+            ->because('of our naming convention');
+
+        $classSet = ClassSet::fromDir(__DIR__.'/../../E2E/_fixtures/mvc');
+
+        $runner = new Runner();
+
+        $runner->check(
+            ClassSetRules::create($classSet, $rule),
+            new VoidProgress(),
+            FileParserFactory::createFileParser(TargetPhpVersion::create()),
+            $violations = new Violations(),
+            new ParsingErrors()
+        );
+
+        self::assertEmpty($violations->toArray());
+    }
+}