The number of mentally retarded offenders in adult correctional institutions was found to be disproportionate to their numbers in the general population, and the majority were from minority groups, reflecting the substantially higher incidence of mental retardation among economically deprived and minority groups. Since little empirical evidence exists to support the notion that subnormal intelligence predisposes a person to criminality, the disproportionate presence of mentally retarded offenders in adult correctional institutions appears to result from administrative and legal artifacts in the justice system, notably the reluctance to place mentally retarded offenders on probation. Although mentally retarded inmates are not segregated from nonretarded inmates, they are offered a variety of educational and vocational opportunities. An examination of the incidence of mentally retarded offenders in juvenile correctional institutions also revealed their percentage to be disproportionate to their presence in the general population, and they were predominantly from minority groups. The existence of Texas legislation that precludes the incarceration of mentally retarded juveniles suggests that the Youth Council is in violation of the law. In comparing the residents of State residential facilities for the mentally retarded with mentally retarded inmates, those in the residential facilities were found to be more profoundly retarded and to have little prior involvement with the criminal justice system, although some were observed to have problematic aggressive behavior. An examination of community-based programs in Jefferson County found that if a person has the dual handicap of mental retardation and delinquency, there are virtually no community-based programs available. A brief summary is given of the results of a national survey on the diagnosis and treatment of mentally retarded offenders in correctional institutions. Twenty-three notes are listed.