If you have a MongoDB document that has another document embedded in it, you still have to create a separate XML mapping document for the embedded one. So if you have a parent document called Activity that has an embedded document called Coordinates , the configuration would look something like this: src/Acme/ActivityBundle/Resources/config/doctrine/Activity.mongodb.xml <doctrine-mongo-mapping xmlns="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping.xsd"> <document name="Acme\ActivityBundle\Document\Activity" db="acme" collection="activity" customId="true"> <field fieldName="id" id="true" strategy="INCREMENT...