The proposed study consists of two phases. The first phase will attempt to identify groups of factors that characterize various types of sex offenders; and the second phase will involve long-term offender follow-up to determine recidivism rates for each type of sex offender. All sex offenders who recidivate will also be reassessed to identify the factors that led to their recidivism. The variables associated with recidivism can be divided into four categories: criminal history (both sex and non- sex offenses); current offense; personal characteristics; and treatment. The proposed study will deal primarily with four categories of personal-characteristics variables that may have the potential to predict recidivism: personal and family history, psychometric data, phallometric data, and pre-crime phase data. The selection of these variables was based on current sexual aggression theories. The study sample will include all sex offenders assessed during their stay at the Regional Reception Centre (Quebec) between February 1995 and January 1997. This description of the study also encompasses the measurement instruments, the procedure, and analytical strategy. 6 footnotes