The first part of the paper considers what is known about the mentally handicapped offender, what service provisions are available, and what treatments are available. The author notes that the choice of treatment must be determined by the potential abilities of the client, especially whether or not the client is verbal; the nature of the offense; whether the client is motivated to change; and the treatment facility. A large proportion of the early literature focused on behavioral treatment, but difficulties have been encountered in the maintenance of behavioral change and the generalization of skills to new environments. An additional criticism is that treatments based on the control of external contingencies may in time decrease self-reliance and foster dependency on caregivers. More recently, the literature has been concerned with treatments designed to help individuals learn to gain control over their own behavior. The treatment program described and assessed focused on anger control for a sample of mentally disordered clients. The treatment lasted for approximately 50 weeks, with 16 weeks allocated to the collection of follow-up data. In one phase of the program clients were given information about anger, and information was obtained on clients' individual anger patterns. Phase two (approximately 25 to 30 weeks) focused on the skills acquisition and application phase. Follow-up data show the treatment to have been effective in reducing anger as a problem behavior. 5 tables and 47 references