The study examined differences in initial and later depressive symptoms of 325 male prisoners based on three levels of custody and four levels of locus of control. Significant differences emerged for groups of prisoners with high internal and external locus of control orientations. The highly internal group was the least depressed at both testings. High externals showed a significant increase in reported depression after a period of adjustment to prison and were the only group with a significant reactive depression. There were no differences in depressive severity based on level of custody or its interaction with control orientation. Depression scores that were initially at either extreme declined so that later, adjustment depression scores fell in the mild and moderate range. The article recommends a general measure of locus of control given at intake to identify prior to imprisonment inmates at risk of subsequently developing depressive disorders. Prisoners at risk can be noted for mental health services or placed in a group designed to help with the transition to prison and to improve problem solving and coping skills. Tables, references