The study sample consisted of 796 adolescents between the ages of 14 and 17 who participated in interviews by the Youth Services Project in St. Louis, Mo. Eighty-six percent were African American; 43 percent of the sample were male, and 57 percent were female. The sample was representative of adolescent service-sector users. The dependent variable, involvement in violent behavior, was measured by an index of 13 categorical items that measured the various types of violent behavior. Independent variables that reflected environmental factors were exposure to violence, deteriorated neighborhoods, deteriorated schools, family instability, negative peer environment, and traumatic experiences. The behavioral independent variables measured were alcohol dependence and abuse, substance dependence and abuse, and posttraumatic stress symptoms. Forty percent of the variance in African American youths' involvement in violent behavior was predicted by the environmental risk factors of exposure to violence, deteriorated school environment, negative peer environment, and traumatic experiences, as well as by the behavioral risk factors of alcohol use and substance use. Gender differences in risk factors were also explored. The results suggest that preventive interventions should have an ecological approach, including a community and individual focus. 2 tables and 57 references