Sex offenders have become the targets of some of the most far-reaching and novel crime legislation in the U.S. Two key innovations in recent decades have been registration and notification laws which, respectively, require that convicted sex offenders provide valid contact information to law enforcement authorities, and that information about sex offenders be made public. Using the evolution of state law during the 1990s and 2000s, we study how registration and notification affect the frequency of reported sex offenses and the incidence of such offenses across victims. We find evidence that registration reduces the frequency of sex offenses by providing law enforcement with information on local sex offenders. As we predict using a simple model of criminal behavior, this decrease in crime is concentrated among “local” victims (e.g., friends, acquaintances, neighbors) with no evidence of less crime occurring against strangers. We also find evidence that notification has reduced crime, but not, as legislators anticipated, by disrupting the criminal conduct of convicted sex offenders. Our results instead suggest that notification deters nonregistered sex offenders, and may, in fact, increase recidivism among registered offenders by reducing the relative attractiveness of a crime-free life. This finding is consistent with work by criminologists showing that notification imposes social and financial costs on registered sex offenders, perhaps offsetting the relative benefits of forgoing criminal activity. We regard this latter finding as important, given that the purpose of notification is to reduce recidivism.