ABSTRACT. Objective: We investigated drinking behavior and sources of alcohol among Native American and White youths, as well as how underage drinking behavior and sources of alcohol may be related to environmental factors. Method: Survey data from a sample of 18,916 youths (8th, 10th, and 12th grades) from Montana were analyzed using hierarchical linear modeling. Survey data were supplemented with county-level economic and census data. Results: Native American youths were more likely than White youths to report drinking and heavy episodic drinking and initiate drinking at a younger age. Native Americans were less likely than Whites to get alcohol from home or from someone younger than age 21 but were more likely to get it from other social sources or through theft from a store. Living in a county with more Native Americans was inversely related to access to alcohol for both White and Native American youths, as well as reduced lifetime, 30-day, and heavy episodic drinking. Living in a county with more single-parent households was positively related to lifetime drinking, 30-day drinking, heavy episodic drinking, and increased access to alcohol through someone younger than age 21 or a stranger. Median income was negatively related to lifetime drinking and ease of access to alcohol and was positively related to accessing alcohol from home without permission, theft, or purchase with a fake ID.