The specialist hypothesis maintains that sexual offenders tend to restrict their offending to sex crimes habitually repeated. The generalist hypothesis, on the other hand, views sex offenders as generalists who commit a variety of offense types along with sex offenses. This review of empirical findings shows that sexual offenders engage in a variety of criminal behaviors, but with a tendency to engage more frequently in sexual crime over time. Developmental criminology provides a promising framework for a better understanding of the development of sexual offenders' offending patterns. To date, most studies have been based on between-group and within-group analyses in which the individual has not been the focus. No study to date has examined within-individual changes in offending over time, which could help in clarifying behavioral processes and patterns in sexual aggressors. This can only be achieved by using repeated measures of criminal activity over the life-course. Such studies are required in order to better understand the developmental course of offending by those who commit sex crimes, as well as the factors linked to particular offense types. This would then facilitate the development of more accurate risk assessment and treatment modalities. 1 table and 95 references