In the past two decades, there has been significant interest among developmental psychopathologists in the study of relational forms of aggression, including gossip, social exclusion, and rumor spreading. This chapter reviews recent advances in research regarding the development of relational aggression in males and females. We focus on conceptual challenges in defining relational aggression, normative and atypical developmental trajectories, and theoretical and empirical work regarding gender differences in such conduct. We also examine potential mechanisms involved in the development of relational aggression, including biobehavioral, cognitive‐emotional, and social risk factors. Next, we discuss both positive and negative developmental outcomes associated with involvement in relational aggression. Implications for both cross‐cultural research and interventions are discussed. Finally, developmental psychopathology perspectives and directions for future research are highlighted.