With a sample of 56 deaf and hard of hearing (DHH) and hearing preschool aged children data on five important developmental domains were collected with the KOMPIK observation scale, which is an instrument on competences and interests of young children. The scale provides as a reliable and viable instrument for the assessment of child competencies. The data reveal significant relations of the children’s developmental status in the domains assessed with the communicative competencies of the children as well as with behaviour disorders. A comparison of groups reveals that DHH children differ from hearing children especially in their social and emotional development and in their language development. The same applies to hearing children with deaf parents. They do also differ in the same domains from hearing children with hearing parents. Consequences for intervention and limitations of the study are discussed.