Evaluated were 500 male inmates admitted to the Texas Department of Corrections over a 2-month period. The study was part of Project CAMIO (Correctional Administration and the Mentally Incompetent Offender), a Texas study to determine the incidence of criminal incarceration of the mentally retarded (MR) and to identify laws, procedures, and practices which affect the prosecution and incarceration of the MR offender. Evaluation of the inmates was undertaken to determine the incidence of MR individuals committed to the Department of Corrections and to determine the relationship between intelligence and aspects of the social and criminal histories of MR offenders. Administered were five intelligence tests and two tests of educational achievement. The MR incidence among Ss was found to be approximately 10% (more than three times the rate within the general population). Evaluation of background characteristics indicated that MR inmates tended to be older, to have no military service, and to be members of minority groups. The non-retarded inmate was more likely to have been granted probation as a juvenile offender or as a previous adult offender, MR and non-MR offenders tended to have similar criminal records, though MR offenders were more likely to have been convicted of crimes of rape and burglary. Findings indicated the most significant difference between MR and non-MR inmates to be in the more frequent granting of probation to the non-MR. (DB)