The study found that higher scores on motivation to change sexually deviant behavior upon entering treatment was associated with retention in treatment. Other factors significantly related to retention in treatment were higher levels of education and admission to treatment within 3 months of initial commitment to prison. The importance of initial motivation to change suggests the value of having motivational enhancement interventions. Also, individuals discharged from the treatment program for disciplinary reasons could be sent to a program that addresses their motivational issues and prepares them for reentry into treatment. The fact that individuals with higher educational levels showed better retention in treatment suggests that attention be given to the reading and comprehension levels of program materials. More rapid involvement in sex offender treatment programs after prison admission could be facilitated by placing those on the waiting list into an outpatient program before admission to the residential program when it is anticipated that admission to the residential program will take longer than 3 months. The study sample consisted of 251 individuals who were admitted to a residential prison-based sex offender treatment program, 46 percent of whom completed the program. Treatment was voluntary. The Stages of Change Questionnaire was used to measure motivation for change. The instructions and some items of the motivation survey were adapted to refer to sexual problems. 3 tables and 40 references