Evaluated the effectiveness of progressive muscle relaxation and systematic desensitization in reducing anger responses of a 26-yr-old mentally retarded man, with an IQ of 70 on the Wechsler Adult Intelligence Scale--Revised (WAIS--R). Desensitization was conducted for 3 provoking stimuli: joke telling, criticism, and heterosexual talk. A multiple baseline analysis demonstrated that the onset of treatment was associated with a reduction of target responses to below a target level established through observations of nonhandicapped individuals. Observations outside of the treatment condition demonstrated that the positive effect generalized to natural settings. A follow-up evaluation demonstrated the durability of treatment. Results are discussed with reference to alternatives to aversive treatments for reducing aggressive responses in dually diagnosed persons with mental retardation. (PsycINFO Database Record (c) 2004 APA, all rights reserved)