Violent aggressive behavior in children has life-long consequences for perpetrators, victims, their families, and society. Yet the biological bases of juvenile aggression remain largely unknown. This gap in knowledge persists due to a lack of tractable models in which juvenile aggression can be readily observed and manipulated. The proposed project takes an innovative, integrative approach to address this pressing knowledge gap using a novel animal model. Alongside the experimental tractability of classic fish and amphibian models, poison frog juveniles are highly aggressive, providing a powerful opportunity to understand the genomic bases of juvenile aggression. We test the central hypothesis that distinct mechanisms mediate the acute performance of, propensity for, and consequences of aggressive experiences. We pursue two complementary research directions to (1) uncover the mechanistic bases of individual variation and developmental shifts in aggression, and (2) probe the genomic and behavioral consequences of aggressive experiences for both perpetrators and victims. To optimize risk and reward, we tackle these questions from multiple angles, combining unbiased, exploratory approaches with characterization and manipulation of canonical candidates important for social behavior across vertebrates, including humans. Experiences of aggression have long-lasting individual and societal consequences and mechanistic research will have a significant positive impact by illuminating causes, consequences, and potential treatments for violent aggression among the youngest members of our society.