The present study investigated the efficiency of various existing measures, mainly psychological tests, for predicting job performance of mentally retarded workers in a sheltered occupational shop. Twenty-two production-related jobs and one nonproduction-related job were analyzed with the Position Analysis Questionnaire resulting in two job attribute clusters. Correlations between 19 predictor variables and 5 criterion variables, which consisted of supervisor ratings of job performance, were then calculated separately for subjects performing preferred jobs in each attribute group. The results indicated that, contrary to past research, existing measures are predictive of performance on some but not all jobs in a sheltered workshop.