Four Mexican-American groups were administered the Attitude Behavior Scale-Mental Retardation (ABS-MR). These included: (1) 50 Special Education and Rehabilitation Workers; (2) 50 parents of mentally retarded children; (3) 50 regular school teachers; and (4) 82 parents of the nonretarded. The purposes were: (1) to investigate their attitudes toward the mentally retarded; and (2) to assess the predictive validity of hypothesized determinants of attitudes, including demographic, socio-psychological, contactual, and knowledge factors. The Guttman conceptual facet analysis scheme was applied toward the goal of credibility of results. Eleven hypotheses were presented, ten of which dealt with certain variables which were predicted to relate to attitudes toward mental retardation. Results were presented and discussed. (TL)