The current study examined the influence of descriptive norms, injunctive norms, perceived outcome expectancies, and ethnicity on marijuana and inhalant use among 2334 American Indian (AI) and White high school students who lived on or near reservations in the United States. Hierarchical multiple regression analyses were conducted with survey data collected during the 2009-2010 and 2010-2011 school years. Results suggest differences between ethnicities in the influence of the normative environment and outcome expectancies on both marijuana and inhalant use. Study limitations are noted, and future research is suggested.