Since the mid-1990s legislators have enacted a series of laws regulating convicted sex offenders who have returned to communities. Policymakers crafted these laws to appease a worried public, but they were based on assumptions about sex offenders’ behaviors that were not well supported by research evidence. In this paper we examine the social context within which these laws were passed and the assumptions behind the three most common sex offender laws – mandatory registration, community notification, and residence restrictions. Next we review the research that has been conducted so far to evaluate the effectiveness of these laws and their unintended consequences. We conclude with a discussion of the lessons learned from these sex offender laws for both policymaking and future research.