The sexual assault of adult women is noteworthy by its huge social and personal cost to the victims, their families, and ultimately society as a whole. The past decade has seen burgeoning research and clinical interest regarding child molesters but a lack of equivalent effort concerning rapists. Rapists are significantly different from child molesters. While considerable heterogeneity exists within this group, there is a lack of distinctiveness when compared to the wider population of serious criminal offenders. These two features of rapists have implications both for research and treatment. We also argue that despite the advances of the last decade this has been in terms of theory proliferation rather than integration, and that major explanatory gaps remain. In particular, there is a need for more middle-level theory that articulates mechanisms and can underpin treatment. Current treatment approaches have typically been developed for child molesters, and while there has been a significant increase in comprehensiveness and sophistication, the evidence for treatment efficacy with rapists remains tentative. Treatment programs need to be tailored to the specific needs of rapists and to the issues of treatment engagement and completion. We conclude with a variety of suggestions for the research agenda over the next decade.