Volume 31 of the International Review of Research in Mental Retardation is a thematic exploration of personality and motivation in persons with mental retardation. Looking at a broad spectrum of intellectual disabilities, Mental Retardation, Personality, and Motivational Systems explores motivation as a moderator for performance and individualized effort. Coverage includes discussions of intrinsic and extrinsic motivation in both mentally retarded and non-retarded children, self-determination, interpersonal decision making in adolescents and adults with mental retardation, interpersonal relationships, and the connection between etiological-specific differences and motivation to form behavioral phenotypes. A final chapter presents a transactional perspective on human ability, relying on constructs of intelligence, cognitive processes, and motivation, with implications for developmental interventions in the lives of persons with mental retardation.