The efficacy of training parents as behavior modifiers of problem behaviors displayed by their seven-year-old severely retarded son was investigated in relationship to targeted problem behaviors including throwing objects, refusing to comply with parental commands, and refusing to sit in a chair at a table. In order to deal with the child's retardation which resulted from a rare chromosomal aberration previously unexplored in the behavioral therapy literature, parents were instructed in a simple behavioral treatment package consisting of verbal punishment and reinforcement. Treatment was assessed according to a multiple baseline across behaviors design. Results showed significant improvement on all three target behaviors following the application of the treatment intervention. Transfer of training to the natural environment was assessed and results revealed maintenance of behavioral improvement in a two-month followup. (Author)