Analyses first examined the developmental course of intimate partner violence (IPV), beginning with trajectories of youth violence. We then examined potential mediators of prior youth violence trajectories in models predicting later IPV perpetration as an outcome. Potential mediators include risks associated with the individual (e.g., current alcohol and drug use and mental health diagnosis), characteristics of a perpetrator's partner (e.g., use of alcohol/drugs and history of antisocial behavior), and aspects of the surrounding community (e.g., neighborhood norms favorable to violence and drug use). Data are from the Seattle Social Development Project, a longitudinal study of over 800 individuals followed from elementary school to young adulthood (age 24). Findings suggest that both chronic and late-increaser patterns of youth violence elevated the likelihood of later IPV perpetration. Partial mediation effects of the relation between youth violence and IPV were found for variables related to one's partner and the surrounding community. Individual characteristics of the perpetrator were not uniquely predictive of IPV when measured as a risk index and modeled along with other risk factors. Findings indicate that the risk of IPV could be lessened by addressing earlier forms of violence and by intervening to reduce risks within and across domains of influence.