Three groups of subjects were tested with three self concept measures. The normal children and normal adult groups were matched to the subnormal group on control variables. The self concept measures used were the Piers-Harris Self Concept Scale for Children, the Tennessee Self Concept Scale and a modified Kelly rating repertory grid. Not all subnormals responded to assessment. Results suggest that subnormal adults and normal adults report similar self concept and that children report self concept which is different from these adult groups. Results also suggest that level of mental age determines the ability to complete a self concept assessment and chronological age determines positive score on self concept assessment. Most of the research in subnormality and self concept has been completed with mildly subnormal subjects. This research is reviewed. There is little previous research in subnormality to which to compare the results of this study.