Some Aboriginal youth are at disproportionate risk of using substances and developing abuse and dependence disorders. However, not all Aboriginal youth misuse substances and limited research has examined the protective factors conferring against substance use among these youth. The present study aimed to identify protective factors related to the alcohol use trajectories from early adolescence to emerging adulthood among off-reserve Canadian Aboriginal youth. Participants (N = 330; 50.3 percent male) aged 12-23 were selected from cycles 2-7 of Statistics Canada's NLSCY. Multilevel modeling was employed to identify protective factors for two constructs of alcohol use. Participation in weekly activities and optimism were found to be protective for both the frequency of alcohol use and heavy drinking trajectories. Attendance of religious services was also found to be protective for heavy drinking behaviors. In contrast, positive peer relationships were a risk factor for frequency of alcohol use, but not heavy drinking. The results provide preliminary evidence of important developmental factors to integrate into substance use intervention programs targeting Aboriginal youth. (Published Abstract)