Specifically, this research attempted to determine whether serious sex offenses are increasing in Western Australia and whether these offenses are committed by specialist offenders. The relationship between the incidence of victimization and the behavior of known offenders is analyzed in terms of the attrition of cases from report, to arrest, trial, conviction, and imprisonment. The data indicate that sex offenders constitute a more representative population than had previously been believed. The effectiveness of treatment programs for sex offenders is reviewed, and the findings suggest that the incidence of sex offenses has remained relatively stable since the mid-1970's; most increases in the reported incidence of sexual assault were a result of increased willingness on the part of victims to report their victimization to the police. A covariate analysis of recidivism data indicated that prior record, age, and race were crucial determining factors for identifying offenders, but little evidence of specialization was found. 16 tables, 7 figures, and 3 appendixes