The purpose of this study was to examine whether cognitive-behavioral therapy could be effective in alleviating depression in mildly mentally retarded or borderline intelligence individuals. It was hoped this would prove to be a viable alternative or adjunct to medical interventions in treating depression with this population. Subjects participated in one of two cognitive-behavioral groups for 12 weeks. Two other treatments (two exercise and two structured, talk-oriented groups) served as control groups; these group members had the same daily routine as individuals in the treatment group. Control group subjects were also administered the same pre- and post-test. Seventy-three subjects were referred to participate, all on a volunteer basis. Subjects resided at the Stockton Developmental Center. All subjects were at the Center involuntarily, with 39 percent committed to the Center due to penal code violations. The Beck Depression Inventory (BDI) was used as a pre-screening device, and subjects scoring in the clinical ranges of depression on the BDI were included in the study. Fifty-eight subjects met pre-screening criteria and were included. Based on BDI scores, subjects were assigned to one of three ranges of depression specified for the BDI. Subjects in each range were then matched on BDI scores and randomly assigned to the treatment groups. The pre- and post-test measure was the Emotional Problems Scales, which include both a personality inventory with questions answered by each individual and a behavior rating scale answered by the individual's primary counselor. Scores on depression and related scales were examined through the multivariate analysis of variance procedure. Forty-nine subjects were included in the final statistical analysis. There was no significant finding across groups for a decrease in depression or for other variables. No treatment proved more effective than any other. An examination of subject characteristics for those demonstrating the highest levels of improvement following treatment found that subjects with scores initially in the extremely severe range on depression were most likely to evidence change in a positive direction. Those who demonstrated improvement in the cognitive-behavioral groups tended to have IQ's over 62.