The Training Proficiency Scale, designed to evaluate the competence of a trainer utilizing operant conditioning techniques with the mentally handicapped, is described in terms of its need, development, reliability and validity qualities, and four areas of assessment (shaping behavior, rewarding, communicating, and rapport). The scale is presented in its entirety, and instructions for scoring are provided. A glossary of terms used in behavior modification research with the mentally retarded is included. (RD)