This study investigated the links between alcohol use trajectories and problem drinking (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition abuse/dependence) using five waves of data from 727 North American Indigenous adolescents between 10 and 17 years from eight reservations sharing a common language and culture. Growth mixture models linking fundamental causes, social stressors, support, and psychosocial pathways to problem drinking via alcohol use trajectories over the early life course were estimated. Results indicated that 20 percent of the adolescents began drinking at 11 to 12 years of age and that another 20 percent began drinking shortly thereafter. These early drinkers were at greatly elevated risk for problem drinking, as were those who began drinking at age 13. The etiological analysis revealed that stressors (e.g., perceived discrimination) directly and indirectly influenced early and problem alcohol use by decreasing positive school attitudes while increasing feelings of anger and perceived delinquent friendships. Girls were found to be at risk independently of these other factors.