Understanding factors that affect the severity of a juvenile-stranger sexual assault has implications for crime prevention, and potentially, the assessment and treatment of juvenile sex offenders. This study investigated how victim characteristics and the number of suspects affected the use of physical violence and weapons and the occurrence of penetration in 495 allegations of sexual assault committed by juveniles against strangers. Statistically significant interactions between victim age and gender were found for occurrence of penetration and use of violence. Differences in offense characteristics were also found between offenses with varying victim-suspect age differences. When comparing the rate of penetration in the presence and absence of violence, little change was observed for lone suspects. However, the rate of penetration increased significantly for groups in the presence of physical violence, suggesting that violence in this context may be more expressive than instrumental. Theoretical explanations and practical implications are considered. (Contains 4 figures and 3 tables.)