To test the hypothesis that experimentally-induced success and failure experiences would differentially affect mentally retarded and normal children, 24 educable mentally retarded children and their matched mental age (MA) and chronological age (CA) controls were given six trials on a verbal 5-item vocabulary task. The subjects (Ss) were given, in counter-balanced design, three success trials (simple words) and three failure trials (difficult words). All Ss gave a prediction of performance estimate for each trial. The retarded Ss and their MA controls set higher estimates across trials than the older CA controls. The retarded Ss also set higher initial estimates. Results were interpreted as being contrary to the hypothesis that retardates have had a greater history of failure experiences resulting in lower generalized expectancy of success. (Author/RJ)