Results indicated that inmates who were administered the PICTS for a second time during the initial session of a psychological program they had volunteered for were less defensive and endorsed more criminal thinking items on the second administration than inmates who were administered the PICTS for a second time as part of a routine follow-up. Despite the changes on the PICTS scores for inmates in the psychological program, the scale relationships of the PICTS changed no more for program participants than they did for control inmates. The findings suggest that it may be the purpose of the evaluation (routine intake versus program enrollment) rather than characteristics of the inmates (volunteer versus nonvolunteer) that makes generalizing results obtained with prison program participants to the general population of inmates problematic. PICTS should therefore not be interpreted in the absence of information about the purpose or context of the evaluation. The study involved the routine intake administration of PICTS, a self-report questionnaire designed to assess criminal lifestyles, to 160 male prisoners as they were admitted to a medium-security Federal correctional facility. Of these inmates, 106 completed the PICTS a second time 6 months later as part of a routine follow-up while another 54 inmates completed the PICTS for a second time approximately 6 months later during the initial session of a voluntary psychological program. The analysis calculated correlations across the two testings for program and control participants and examined whether group and time would interact to produce differences in PICTS scores across the testings. Tables, notes, references