diff --git a/lib/Doctrine/ORM/ORMInvalidArgumentException.php b/lib/Doctrine/ORM/ORMInvalidArgumentException.php
new file mode 100644
index 000000000..b4edc5dd2
--- /dev/null
+++ b/lib/Doctrine/ORM/ORMInvalidArgumentException.php
@@ -0,0 +1,81 @@
+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\ORM;
+
+class ORMInvalidArgumentException extends \InvalidArgumentException
+{
+    static public function scheduleInsertForManagedEntity($entity)
+    {
+        return new self("A managed+dirty entity " . self::objToStr($entity) . " can not be scheduled for insertion.");
+    }
+
+    static public function scheduleInsertForRemovedEntity($entity)
+    {
+        return new self("Removed entity " . self::objToStr($entity) . " can not be scheduled for insertion.");
+    }
+
+    static public function scheduleInsertTwice($entity)
+    {
+        return new self("Entity " . self::objToStr($entity) . " can not be scheduled for insertion twice.");
+    }
+
+    static public function entityWithoutIdentity($className, $entity)
+    {
+        throw new self(
+            "The given entity of type '" . $className . "' (".self::objToStr($entity).") has no identity/no " . 
+            "id values set. It cannot be added to the identity map."
+        );
+    }
+
+    static public function readOnlyRequiresManagedEntity($entity)
+    {
+        return new self("Only managed entities can be marked or checked as read only. But " . self::objToStr($entity) . " is not");
+    }
+
+    static public function newEntityFoundThroughRelationship(array $assoc, $entry)
+    {
+        return new self("A new entity was found through the relationship '"
+                            . $assoc['sourceEntity'] . "#" . $assoc['fieldName'] . "' that was not"
+                            . " configured to cascade persist operations for entity: " . self::objToStr($entry) . "."
+                            . " To solve this issue: Either explicitly call EntityManager#persist()"
+                            . " on this unknown entity or configure cascade persist "
+                            . " this association in the mapping for example @ManyToOne(..,cascade={\"persist\"}). "
+                            . " If you cannot find out which entity causes the problem"
+                            . " implement '" . $assoc['targetEntity'] . "#__toString()' to get a clue.");
+    }
+
+    static public function detachedEntityFoundThroughRelationship(array $assoc, $entry)
+    {
+        throw new self("A detached entity of type " . $assoc['targetEntity'] . " (" . self::objToStr($entry) . ") "
+                        . " was found through the relationship '" . $assoc['sourceEntity'] . "#" . $assoc['fieldName'] . "' "
+                        . "during cascading a persist operation.");
+    }
+
+    /**
+     * Helper method to show an object as string.
+     *
+     * @param  object $obj
+     * @return string
+     */
+    private static function objToStr($obj)
+    {
+        return method_exists($obj, '__toString') ? (string)$obj : get_class($obj).'@'.spl_object_hash($obj);
+    }
+}
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 1e6d13fb5..2b696063f 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -595,25 +595,16 @@ class UnitOfWork implements PropertyChangedListener
             $oid = spl_object_hash($entry);
             if ($state == self::STATE_NEW) {
                 if ( ! $assoc['isCascadePersist']) {
-                    throw new InvalidArgumentException("A new entity was found through the relationship '"
-                            . $assoc['sourceEntity'] . "#" . $assoc['fieldName'] . "' that was not"
-                            . " configured to cascade persist operations for entity: " . self::objToStr($entry) . "."
-                            . " Explicitly call EntityManager#persist() on this entity or configure to cascade persist "
-                            . " the association. If you cannot find out which entity causes the problem"
-                            . " implement '" . $assoc['targetEntity'] . "#__toString()' to get a clue.");
+                    throw ORMInvalidArgumentException::newEntityFoundThroughRelationship($assoc, $entry);
                 }
                 $this->persistNew($targetClass, $entry);
                 $this->computeChangeSet($targetClass, $entry);
-            } else if ($state == self::STATE_REMOVED) {
-                return new InvalidArgumentException("Removed entity detected during flush: "
-                        . self::objToStr($entry).". Remove deleted entities from associations.");
             } else if ($state == self::STATE_DETACHED) {
                 // Can actually not happen right now as we assume STATE_NEW,
                 // so the exception will be raised from the DBAL layer (constraint violation).
-                throw new InvalidArgumentException("A detached entity was found through a "
-                        . "relationship during cascading a persist operation.");
+                throw ORMInvalidArgumentException::detachedEntityFoundThroughRelationship($assoc, $entry);
             }
-            // MANAGED associated entities are already taken into account
+            // MANAGED and REMOVED associated entities are already taken into account
             // during changeset calculation anyway, since they are in the identity map.
         }
     }
@@ -662,7 +653,7 @@ class UnitOfWork implements PropertyChangedListener
         $oid = spl_object_hash($entity);
         
         if ( ! isset($this->entityStates[$oid]) || $this->entityStates[$oid] != self::STATE_MANAGED) {
-            throw new InvalidArgumentException('Entity must be managed.');
+            throw new InvalidArgumentException("Entity of type '" . $class->name . "' must be managed.");
         }
         
         /* TODO: Just return if changetracking policy is NOTIFY?
@@ -907,14 +898,14 @@ class UnitOfWork implements PropertyChangedListener
     {
         $oid = spl_object_hash($entity);
 
-        if (isset($this->entityUpdates[$oid])) {
-            throw new InvalidArgumentException("Dirty entity can not be scheduled for insertion.");
-        }
         if (isset($this->entityDeletions[$oid])) {
-            throw new InvalidArgumentException("Removed entity can not be scheduled for insertion.");
+            throw ORMInvalidArgumentException::scheduleInsertForRemovedEntity($entity);
+        }
+        if (isset($this->originalEntityData[$oid]) && ! isset($this->entityInsertions[$oid])) {
+            throw ORMInvalidArgumentException::scheduleInsertForManagedEntity($entity);
         }
         if (isset($this->entityInsertions[$oid])) {
-            throw new InvalidArgumentException("Entity can not be scheduled for insertion twice.");
+            throw ORMInvalidArgumentException::scheduleInsertTwice($entity);
         }
 
         $this->entityInsertions[$oid] = $entity;
@@ -1071,7 +1062,7 @@ class UnitOfWork implements PropertyChangedListener
         $classMetadata = $this->em->getClassMetadata(get_class($entity));
         $idHash = implode(' ', $this->entityIdentifiers[spl_object_hash($entity)]);
         if ($idHash === '') {
-            throw new InvalidArgumentException("The given entity has no identity.");
+            throw ORMInvalidArgumentException::entityWithoutIdentity($classMetadata->name, $entity);
         }
         $className = $classMetadata->rootEntityName;
         if (isset($this->identityMap[$className][$idHash])) {
@@ -2466,7 +2457,7 @@ class UnitOfWork implements PropertyChangedListener
     public function markReadOnly($object)
     {
         if ( ! is_object($object) || ! $this->isInIdentityMap($object)) {
-            throw new InvalidArgumentException("Managed entity required");
+            throw ORMInvalidArgumentException::readOnlyRequiresManagedEntity($object);
         }
         $this->readOnlyObjects[spl_object_hash($object)] = true;
     }
@@ -2481,7 +2472,7 @@ class UnitOfWork implements PropertyChangedListener
     public function isReadOnly($object)
     {
         if ( ! is_object($object) ) {
-            throw new InvalidArgumentException("Managed entity required");
+            throw ORMInvalidArgumentException::readOnlyRequiresManagedEntity($object);
         }
         return isset($this->readOnlyObjects[spl_object_hash($object)]);
     }
diff --git a/tests/Doctrine/Tests/ORM/Functional/UnitOfWorkLifecycleTest.php b/tests/Doctrine/Tests/ORM/Functional/UnitOfWorkLifecycleTest.php
new file mode 100644
index 000000000..08e3720ca
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/UnitOfWorkLifecycleTest.php
@@ -0,0 +1,71 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional;
+
+use Doctrine\Tests\Models\CMS\CmsUser;
+
+class UnitOfWorkLifecycleTest extends \Doctrine\Tests\OrmFunctionalTestCase
+{
+    protected function setUp()
+    {
+        $this->useModelSet('cms');
+        parent::setUp();
+    }
+
+    public function testScheduleInsertManaged()
+    {
+        $user = new CmsUser();
+        $user->username = "beberlei";
+        $user->name = "Benjamin";
+        $user->status = "active";
+        $this->_em->persist($user);
+        $this->_em->flush();
+
+        $this->setExpectedException("Doctrine\ORM\ORMInvalidArgumentException", "A managed+dirty entity Doctrine\Tests\Models\CMS\CmsUser");
+        $this->_em->getUnitOfWork()->scheduleForInsert($user);
+    }
+
+    public function testScheduleInsertDeleted()
+    {
+        $user = new CmsUser();
+        $user->username = "beberlei";
+        $user->name = "Benjamin";
+        $user->status = "active";
+        $this->_em->persist($user);
+        $this->_em->flush();
+
+        $this->_em->remove($user);
+
+        $this->setExpectedException("Doctrine\ORM\ORMInvalidArgumentException", "Removed entity Doctrine\Tests\Models\CMS\CmsUser");
+        $this->_em->getUnitOfWork()->scheduleForInsert($user);
+    }
+
+    public function testScheduleInsertTwice()
+    {
+        $user = new CmsUser();
+        $user->username = "beberlei";
+        $user->name = "Benjamin";
+        $user->status = "active";
+
+        $this->_em->getUnitOfWork()->scheduleForInsert($user);
+
+        $this->setExpectedException("Doctrine\ORM\ORMInvalidArgumentException", "Entity Doctrine\Tests\Models\CMS\CmsUser");
+        $this->_em->getUnitOfWork()->scheduleForInsert($user);
+    }
+
+    public function testAddToIdentityMapWithoutIdentity()
+    {
+        $user = new CmsUser();
+
+        $this->setExpectedException("Doctrine\ORM\ORMInvalidArgumentException", "The given entity of type 'Doctrine\Tests\Models\CMS\CmsUser' (Doctrine\Tests\Models\CMS\CmsUser@");
+        $this->_em->getUnitOfWork()->registerManaged($user, array(), array());
+    }
+
+    public function testMarkReadOnlyNonManaged()
+    {
+        $user = new CmsUser();
+
+        $this->setExpectedException("Doctrine\ORM\ORMInvalidArgumentException", "Only managed entities can be marked or checked as read only. But Doctrine\Tests\Models\CMS\CmsUser@");
+        $this->_em->getUnitOfWork()->markReadOnly($user);
+    }
+}
\ No newline at end of file