Certain aspects of the use of the Snijders-Oomen Non-verbal Intelligence Test (SON-R 6-40) in clinical and educational assessment of children with hearing impairment and children from immigrant families are discussed. Test results of 35 children per group have been compared to the data from a German-speaking control group, matched by age, sex and educational achievement of both parents. Specific differences between the three groups on both subtest and IQ levels are demonstrated. This paper provides scoring results for the three groups and discusses the differences between the test profiles. The test can be accomplished with children who have special educational needs. Results also prove the usefulness of a non verbal test in the assessment of cognitive abilities in clinical-diagnostic questions.