This study explores differences between patients who completed outpatient sex offender treatment and those who dropped out prior to completion. Subjects were 173 men who entered outpatient treatment after having committed a sexual offense; Seventy-nine subjects who successfully completed treatment, and 94 who did not Two questions are addressed: First, what demographic factors, offending patterns, and psychological characteristics are related to completion of treatment; and second, are there differences in reoffending behaviors depending on whether or not one completes treatment? Two psychometric measures were used: the Minnesota Multiphasic Personality Inventory (MMPI) and the Tennessee Self-Concept Scale. Official arrest and conviction records were requested from Minnesota and surrounding jurisdictions. The results indicate that there are demographic and psychological factors that differentiate those who complete treatment from those who do not, and that those who fail to complete treatment do appear.