The study found adequate reliability (internal consistency and interrater reliability) for J-SOAP-II total score and most subscale scores, although there was some variability among the individual subscales. There was moderate to high levels of predictive validity when analyzing the relationship between J-SOAP-II scores and reoffense data and treatment outcome, although again with substantial variability among the subscales. The study found the strongest support for the Dynamic Summary scale of J-SOAP-II; it had high reliability and the greatest accuracy in predicting reoffense and treatment outcome, providing a unique contribution above and beyond that of the Static Summary scale. More research is needed in order to determine the utility and limitations of various risk-assessment instruments for sex offenders across the entire spectrum of risk, particularly for young offenders. The J-SOAP-II consists of four subscales. The first two compose the Static Summary scale, and the last two compose the Dynamic Summary scale. Subscale 1 addresses Sexual Drive/Preoccupation; subscale 2 targets Antisocial Behavior/Impulsivity; subscale 3 addresses Intervention History; and subscale 4 focuses on Community Stability, Adjustment, or Support. The study included all 60 adolescent boys admitted to a community-based adolescent sex-offender treatment program between 1996 and 2004. They ranged in age from 12 to 18. All had been accused, suspected, or found guilty of a sexual offense against children, peers, or adults; and all had admitted to at least some of the accusations against them. 4 tables and 37 references