diff --git a/src/Builder/BuilderAbstract.php b/src/Builder/BuilderAbstract.php
index 6ec23a6..eff9686 100644
--- a/src/Builder/BuilderAbstract.php
+++ b/src/Builder/BuilderAbstract.php
@@ -3,20 +3,29 @@
 namespace ABC\Builder;
 
 use \ABC\Builder\BuilderAction;
+use \Exception;
 
 abstract class BuilderAbstract
 {
     /** @var array(\ABC\Builder\BuilderAction) */
     public $builderActions = array();
 
+    /** @var bool */
+    public $executed       = false;
+
+    /** @var array(callable) */
+    public $validations    = array();
+
     /**
      * @return null
      */
-    public function executeActions()
+    public function execute()
     {
         foreach ($this->builderActions as $action) {
             call_user_func_array($action->action, $action->arguments);
         }
+        $this->validate();
+        $this->executed = true;
         return $this;
     }
 
@@ -28,4 +37,60 @@ public function addAction($action)
         $this->builderActions[] = $action;
         return $this;
     }
+
+    /**
+     * @throws \Exception
+     */
+    public function checkStatus()
+    {
+        if (!$this->executed) {
+            throw new Exception('Builder actions not executed');
+        }
+    }
+
+    /**
+     * @throws \Exception
+     */
+    protected function validate()
+    {
+        $actions = $this->compileActionCounts();
+        foreach ($this->validations as $validation) {
+            $result = call_user_func_array($validation['callback'], array($actions));
+            if (!$result) {
+                $class = $validation['exceptionType'];
+                throw new $class($validation['exceptionMessage']);
+            }
+        }
+    }
+
+    /**
+     * @return array
+     */
+    protected function compileActionCounts()
+    {
+        $counts = array();
+
+        foreach ($this->builderActions as $action) {
+            $counts[$action->name] = isset($counts[$action->name]) ? $counts[$action->name]+1 : 1;
+        }
+
+        return $counts;
+    }
+
+    /**
+     * @param callable $callback
+     * @param string   $exceptionType
+     * @param string   $exceptionMessage
+     *
+     * @return \ABC\Builder\BuilderAbstract
+     */
+    protected function addValidation($callback, $exceptionType, $exceptionMessage = '')
+    {
+        $this->validations[] = array(
+            'callback' => $callback,
+            'exceptionType' => $exceptionType,
+            'exceptionMessage' => $exceptionMessage,
+        );
+        return $this;
+    }
 }
diff --git a/src/Builder/CompanyBuilder.php b/src/Builder/CompanyBuilder.php
index d9306f0..14f595d 100644
--- a/src/Builder/CompanyBuilder.php
+++ b/src/Builder/CompanyBuilder.php
@@ -10,17 +10,20 @@
 
 class CompanyBuilder extends BuilderAbstract
 {
+    /** @var \ABC\Builder\Company */
     public $company      = null;
 
-    public function __construct($company = null)
+    public function __construct()
     {
-        if ($company != null) {
-            $this->company = $company;
-        } else {
-            $this->company = new Company();
-        }
+        $this->company = new Company();
+        $this->setUpValidations();
     }
 
+    /**
+     * @param \ABC\Builder\Address $address
+     *
+     * @return \ABC\Builder\Company
+     */
     public function withAddress(Address $address)
     {
         $action = new CompanyBuilderAction('withAddress', array($this->company, 'appendAddress'));
@@ -29,6 +32,11 @@ public function withAddress(Address $address)
         return $this;
     }
 
+    /**
+     * @param \ABC\Builder\Person $person
+     *
+     * @return \ABC\Builder\Company
+     */
     public function withPerson(Person $person)
     {
         $action = new CompanyBuilderAction('withPerson', array($this->company, 'appendPerson'));
@@ -37,13 +45,34 @@ public function withPerson(Person $person)
         return $this;
     }
 
+    /**
+     * Returns executed object as JSON.
+     * Throws an exception when builder actions
+     * have not been executed.
+     *
+     * @throws \Exception
+     *
+     * @return string
+     */
     public function asJson()
     {
+        $this->checkStatus();
         return json_encode($this->company);
     }
 
+    /**
+     * Returns executed object as XML.
+     * Throws an exception when builder actions
+     * have not been executed.
+     *
+     * @throws \Exception
+     *
+     * @return string
+     */
     public function asXml()
     {
+        $this->checkStatus();
+
         $xml = new DOMDocument('1.0', 'utf-8');
         $company = $xml->createElement('Company');
 
@@ -75,4 +104,40 @@ public function asXml()
 
         return $xml->saveXml();
     }
+
+    /**
+     * Ensures there is at least one address.
+     *
+     * @param arraay $actionCounts
+     *
+     * @return bool
+     */
+    public function atLeastOneAddress($actionCounts)
+    {
+        return isset($actionCounts['withAddress']) && $actionCounts['withAddress'] > 0;
+    }
+
+    /**
+     * Ensures there is at least one person.
+     *
+     * @param arraay $actionCounts
+     *
+     * @return bool
+     */
+    public function atLeastOnePerson($actionCounts)
+    {
+        return isset($actionCounts['withPerson']) && $actionCounts['withPerson'] > 0;
+    }
+
+    /**
+     * Setups up validations for building Company objects.
+     *
+     * @return null
+     */
+    private function setUpValidations()
+    {
+        $this
+            ->addValidation(array($this, 'atLeastOneAddress'), 'Exception', 'Company needs at least one address')
+            ->addValidation(array($this, 'atLeastOnePerson'), 'Exception', 'Company needs at least one person');
+    }
 }
diff --git a/tests/Builder/AddressBuilderTest.php b/tests/Builder/AddressBuilderTest.php
index 8b47187..bf88c66 100644
--- a/tests/Builder/AddressBuilderTest.php
+++ b/tests/Builder/AddressBuilderTest.php
@@ -14,7 +14,7 @@ public function testBuilderWithInitialValueNoActions()
 
         $this->assertEquals($this->expectedAddress(), $builder->address);
 
-        $builder = $builder->executeActions();
+        $builder = $builder->execute();
 
         $this->assertEquals($this->expectedAddress(), $builder->address);
     }
@@ -23,7 +23,7 @@ public function testBuilderWithoutInitialValueNoActions()
     {
         $builder = new AddressBuilder();
 
-        $builder = $builder->executeActions();
+        $builder = $builder->execute();
 
         $this->assertEquals(new Address(), $builder->address);
     }
diff --git a/tests/Builder/CompanyBuilderTest.php b/tests/Builder/CompanyBuilderTest.php
index e5e058f..7ced8e2 100644
--- a/tests/Builder/CompanyBuilderTest.php
+++ b/tests/Builder/CompanyBuilderTest.php
@@ -20,54 +20,68 @@ public function testBuilderExecutionAddsValuesToProperties()
 
         $this->assertEquals(new Company(), $builder->company);
 
-        $builder = $builder->executeActions();
+        $builder = $builder->execute();
 
         $this->assertEquals($this->expectedCompany(), $builder->company);
     }
 
-    public function testBuilderWithInitialValueNoActions()
+    /** 
+     * @expectedException        \Exception
+     * @expectedExceptionMessage Builder actions not executed
+     */
+    public function testNonExecutedBuilderAsJson()
     {
-        $builder = new CompanyBuilder($this->expectedCompany());
-
-        $this->assertEquals($this->expectedCompany(), $builder->company);
-
-        $builder = $builder->executeActions();
-
-        $this->assertEquals($this->expectedCompany(), $builder->company);
+        $builder = new CompanyBuilder();
+        $json = $builder->asJson();
     }
 
-    public function testBuilderWithInitialValueSomeActions()
+    /** 
+     * @expectedException        \Exception
+     * @expectedExceptionMessage Builder actions not executed
+     */
+    public function testNonExecutedBuilderAsXml()
     {
-        $company = new Company();
-        $company->addresses = array($this->address());
-
-        $builder = new CompanyBuilder($company);
-        $builder = $builder
-            ->withPerson($this->person1())
-            ->withPerson($this->person2());
-
-        $builder = $builder->executeActions();
+        $builder = new CompanyBuilder();
+        $xml = $builder->asXml();
+    }
 
-        $this->assertEquals($this->expectedCompany(), $builder->company);
+    /**
+     * @expectedException        \Exception
+     * @expectedExceptionMessage Company needs at least one address
+     */
+    public function testNonValidBuilderThrowsException()
+    {
+        $builder = new CompanyBuilder();
+        $builder = $builder->execute();
     }
 
     public function testBuilderAsJson()
     {
-        $builder = new CompanyBuilder($this->expectedCompany());
-        $json = $builder->asJson();
+        $builder = new CompanyBuilder();
+        $json = $builder
+            ->withAddress($this->address())
+            ->withPerson($this->person1())
+            ->withPerson($this->person2())
+            ->execute()
+            ->asJson();
 
-        $this->assertEquals($this->expectedJson(), $json);
+        $this->assertJsonStringEqualsJsonString($this->expectedJson(), $json);
     }
 
     public function testBuilderAsXml()
     {
-        $builder = new CompanyBuilder($this->expectedCompany());
-        $xml = $builder->asXml();
+        $builder = new CompanyBuilder();
+        $xml = $builder
+            ->withAddress($this->address())
+            ->withPerson($this->person1())
+            ->withPerson($this->person2())
+            ->execute()
+            ->asXml();
 
         $this->assertXmlStringEqualsXmlString($this->expectedXml(), $xml);
     }
 
-    /** @var \ABC\Builder\Company */
+    /** @return \ABC\Builder\Company */
     protected function expectedCompany()
     {
         $company = new Company();
@@ -76,19 +90,65 @@ protected function expectedCompany()
         return $company;
     }
 
-    /** @var string */
+    /** @return string */
     protected function expectedJson()
     {
-        return '{"name":null,"addresses":[{"address1":null,"address2":null,"city":null,"province":null,"country":null,"postalCode":"12345"}],"people":[{"firstName":"John","lastName":"Smith","address":null},{"firstName":"Tom","lastName":"Smith","address":null}]}';
+        return '{
+                    "name":null,
+                    "addresses":[
+                        {
+                            "address1":null,
+                            "address2":null,
+                            "city":null,
+                            "province":null,
+                            "country":null,
+                            "postalCode":"12345"
+                        }
+                    ],
+                    "people":[
+                        {
+                            "firstName":"John",
+                            "lastName":"Smith",
+                            "address":null
+                        },
+                        {
+                            "firstName":"Tom",
+                            "lastName":"Smith",
+                            "address":null
+                        }
+                    ]
+                }';
     }
 
-    /** @var string */
+    /** @return string */
     protected function expectedXml()
     {
-        return "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<Company><Addresses><Address><Address1/><Address2/><City/><State/><PostalCode>12345</PostalCode><Country/></Address></Addresses><Employees><Person><FirstName>John</FirstName><LastName>Smith</LastName></Person><Person><FirstName>Tom</FirstName><LastName>Smith</LastName></Person></Employees></Company>\n";
+        return "<?xml version=\"1.0\" encoding=\"utf-8\"?>
+                <Company>
+                    <Addresses>
+                        <Address>
+                            <Address1/>
+                            <Address2/>
+                            <City/>
+                            <State/>
+                            <PostalCode>12345</PostalCode>
+                            <Country/>
+                        </Address>
+                    </Addresses>
+                    <Employees>
+                        <Person>
+                            <FirstName>John</FirstName>
+                            <LastName>Smith</LastName>
+                        </Person>
+                        <Person>
+                            <FirstName>Tom</FirstName>
+                            <LastName>Smith</LastName>
+                        </Person>
+                    </Employees>
+                </Company>";
     }
 
-    /** @var \ABC\Builder\Address */
+    /** @return \ABC\Builder\Address */
     protected function address()
     {
         $address = new Address();
@@ -96,7 +156,7 @@ protected function address()
         return $address;
     }
 
-    /** @var \ABC\Builder\Person */
+    /** @return \ABC\Builder\Person */
     protected function person1()
     {
         $person = new Person();
@@ -105,7 +165,7 @@ protected function person1()
         return $person;
     }
 
-    /** @var \ABC\Builder\Person */
+    /** @return \ABC\Builder\Person */
     protected function person2()
     {
         $person = new Person();
diff --git a/tests/Builder/PersonBuilderTest.php b/tests/Builder/PersonBuilderTest.php
index 7aae9d6..787e805 100644
--- a/tests/Builder/PersonBuilderTest.php
+++ b/tests/Builder/PersonBuilderTest.php
@@ -14,7 +14,7 @@ public function testBuilderWithInitialValueNoActions()
 
         $this->assertEquals($this->expectedPerson(), $builder->person);
 
-        $builder = $builder->executeActions();
+        $builder = $builder->execute();
 
         $this->assertEquals($this->expectedPerson(), $builder->person);
     }
@@ -23,7 +23,7 @@ public function testBuilderWithoutInitialValueNoActions()
     {
         $builder = new PersonBuilder();
 
-        $builder = $builder->executeActions();
+        $builder = $builder->execute();
 
         $this->assertEquals(new Person(), $builder->person);
     }