This study examined polygraph-assisted admissions of cross over behaviors in two groups of sexual offenders: (1) inmates participating in intensive prison-based sex offender treatment; and (2) parolees participating in a less intensive community-based treatment. Previous studies have found that treatment combined with polygraph testing is effective in eliciting disclosures of victims and offenses not previously known to the criminal justice system. The researchers expected to find a similar increase in disclosures in this study. It was also expected that there would be more crossover when the data were expanded beyond that typically available to the criminal justice system. Participants were 489 adult male sexual offenders. Data were collected on the inmates and parolees between October 1995 and January 2001. The results show high rates of crossover sexual offenses in the inmate sample. The intensity of treatment and the type of supervision that were combined with polygraph testing were found to be critical factors in the rate of crossover admissions. Parolees that received low intensity treatment admitted substantially fewer crossover offenses than did inmates that received intensive treatment. Both groups admitted more offenses than were identified in official records. Some of the explanations for the difference in the rate of crossover admissions for the inmate and parolee groups are (1) the inmates appear to be more serious offenders; (2) inmates must admit to a sex offense to participate in programs; and (3) the sensitization process regarding the behaviors that constitute a sexual assault. Inmates may have perceived fewer negative consequences for disclosing additional sex offenses. Parolees may have anticipated further restrictions as a result of additional disclosures. It is likely that the intensive prison-based sex offender treatment program was more effective than the low intensity community treatment in eliciting admissions of crossover offending. 4 tables, 40 references