Given widespread recognition of sexual violence as a public health concern, sexual harassment has garnered considerable attention from researchers and the public. Yet research with adolescent samples has typically focused on the experiences of victims rather than perpetrators, and males as perpetrators and females as victims. In the current article, we consider whether risk and protective factors operate similarly within and across sex assigned at birth. A national sample of youth, ages 14 and 15, were recruited via social media and surveyed online (N = 1,981). At the individual level, girls who sexually harassed others, were more likely to have a propensity to respond to stimuli with anger compared to boys who sexually harassed. At the relational level, girls who sexually harassed were more likely to be victims of sexual harassment compared to boys, and having a negative peer environment (have delinquent peers, seen someone get attacked, and know someone who has been sexually assaulted) was of particular importance in understanding why girls harass others. For boys who harass, family relations, having seen or heard about peer physical or sexual assault and bullying perpetration were important for contextualizing boys' sexual harassment. As empathy increased, the relative odds of sexually harassing decreased for girls. Future research should explore motivations for perpetrating sexual harassment, bystander interventions, and longitudinal frameworks to identify causal patterns to determine which factors inhibit or facilitate sexual harassment.