After a review of the literature on the entry period into custody, the chapter presents an overview of the transitional process and examines the common themes of prisoners' descriptions of their custodial experiences. These themes include uncertainty, losing control and freedom, separation and loss, and a preoccupation with safety. Although these were common themes, the inmates differed in the degree to which they experienced these aspects of transition into prison and in the extent to which they felt distressed. Individual differences in locus of control and perceptions of safety explained some of the differences in the levels of distress experienced by the inmates. Inmates who were more internal in their locus of control reported lower levels of psychological distress after 3 days in custody. This confirms previous research findings that individuals with an internal locus of control adapted more successfully to prison life. Persons with a high internal locus of control have been found to have lower levels of depression and anxiety. Individuals who scored higher on the dimension "perceived safety" reported lower levels of psychological distress. A small but significant correlation was found between locus of control and perceived safety. 3 tables, 9 notes, and 34 references