Purpose <p>Although conflict has long been a central focus of sibling studies, sibling violence remain an understudied type of family violence. Moreover, the heterogeneity in trajectories in sibling violence victimization during adolescence and the implications of these constructs for later romantic relationships have been less examined. The purpose of the current study was to identify different trajectories of sibling violence from early to middle adolescence and examine the spillover effect from sibling violence trajectory group memberships to intimate partner violence (IPV) in emerging adulthood.</p> Method <p>Data came from 451 adolescents (52% girls) collected annually from age 13 to 16 and at age 21.</p> Results <p>Using growth mixture modeling, three sibling violence victimization trajectory classes from early to middle adolescence were identified: low-stable (78.9%), increasing (16.2%), and high-decreasing (4.9%). Number of siblings, birth order, and sibling warmth were significantly associated with these trajectory group memberships. The increasing sibling violence trajectory class was associated with higher levels of IPV victimization at age 21.</p> Conclusions <p>Findings can guide intervention efforts by emphasizing the long-lasting history and patterns of sibling violence, especially considering its impact on later romantic relationships.</p>