The recent rise in arrest rates for violent offenses among girls has sparked an increased interest in understanding the risk and protective factors associated with girls’ aggression. Particular attention has been drawn to the role that girls’ intimate relationships may play in promoting persistence or desistence from delinquency. To this end, a number of independent laboratories have been engaged in conducting prospective longitudinal studies to uncover the influence of romantic relationships on girls’ antisocial behavior through the transition from adolescence to emerging adulthood, which are gathered together in this special section. This article introduces the contributions to the special section and considers both the lessons provided and the directions needed for future research devoted to understanding girls’ delinquency and aggression.