Antisocial behavior and substance misuse are forms of problem behavior demonstrating considerable continuity over time. Accordingly, problem behavior influences interpersonal contexts across the life course, which may result in the replication of coercive interactions and a problem behavior lifestyle within romantic relationships. Furthermore, theories of self-selection, and associated research, suggest that individuals pick companions compatible with, and supportive of, their behavior, leading to high levels of similarity between romantic partners and the potential reinforcement of problem behavior over time. However, some research suggests that romantic relationships may play a positive role and facilitate desistance from problem behavior. The purpose of this paper is to explore how antisocial behavior and substance use both influence and are influenced by romantic relationships in late adolescence and early adulthood. We first review research regarding the extent of, and processes underlying, partner similarity in problem behavior. Next, we examine how romantic relationships may promote the desistance of problem behavior. Finally, we discuss possible moderators of the association between problem behavior and romantic relationships, as well as limitations, intergenerational implications, and recommended future directions of the reviewed research.