THE RELATIONSHIPS OF THE SELF-CONCEPTS, LEVELS OF ASPIRATION, AND EMOTIONAL REACTIONS OF MENTALLY RETARDED CHILDREN TO THEIR PROBLEM-SOLVING SITUATIONS AND INDIVIDUAL LEARNING EFFICIENCIES WERE STUDIED, USING NORMALLY DEVELOPING AND BRIGHT STUDENTS FOR COMPARISON. A GROUP OF 40 FOURTH-GRADE CHILDREN WAS SELECTED TO REPRESENT EACH OF THE ABOVE THREE CHILD CATEGORIES. PSYCHOLOGICAL, MEDICAL, AND SCHOLASTIC ACHIEVEMENT DATA WERE ADMINISTERED, COLLECTED, AND EVALUATED FOR EACH PARTICIPANT OVER A 2-YEAR PERIOD. STUDY RESULTS SHOW THAT MENTALLY RETARDED SUBJECTS MAY BE CHARACTERIZED AS BEING EAGER TO PLEASE, FRIENDLY, REASONABLY HAPPY IN THEIR CLASSROOMS, BUT EXHIBITING UNDERLYING ANXIETY. THEY ARE NOT AS REACTIVE TO STIMULI NOR DO THEY APPEAR TO DIFFERENTIATE STIMULI IN THE SAME MANNER AS AVERAGE OR BRIGHT SUBJECTS. THE RETARDED ARE NOT REALISTIC IN SELF-CONCEPT, NOR RELIABLE IN VERBALIZING SELF-CONCEPTS, AND DO NOT DIFFERENTIATE AREAS OF THE SELF-CONCEPT WELL. LEVELS OF ASPIRATION ARE UNREALISTIC AND UNRELIABLE, AND EFFICIENCY OF PROBLEM-SOLVING OR LEARNING OF ARITHMETIC IS LOW. HOWEVER, INDIVIDUAL DIFFERENCES ARE FOUND AMONG THE RETARDED, AS AMONG OTHER SUBJECTS, AND SOME DID UNEXPECTEDLY WELL IN CERTAIN AREAS MEASURED. A GREAT DEAL OF WORK STILL NEEDS TO BE DONE IN AREAS SAMPLED IN THIS STUDY, AND SUGGESTIONS ARE INCLUDED WITHIN EACH SECTION. (JH)