Objective:Marijuana use is relatively common among youth and increases during the transition to adulthood. Yet a substantial number of adolescents and young adults do not use marijuana. The purpose of this study was to examine how high school seniors' reasons for intending not to use marijuana within the next 12 months were prospectively associated with marijuana use reported 1 year later.Method:Data were drawn from national longitudinal samples of U.S. high school seniors from the Monitoring the Future study (n = 3,044; 50% female; 65% White). Bivariate and multivariable logistic regression analyses were conducted to examine associations between reasons seniors indicated for intending not to use marijuana within the next 12 months and marijuana use reported 1 year later in the follow-up survey, controlling for sociodemographic characteristics and high school risk factors. Analyses were conducted separately among youth with and without lifetime marijuana use in high school.Results:In multivariable models, reasons associated with marijuana abstinence 1 year later among prior marijuana use abstainers were concerns about becoming addicted, use being against ones' beliefs, not liking marijuana users, and not having friends who use marijuana. Among prior marijuana users, not enjoying marijuana was a significant predictor of marijuana abstinence 1 year later.Conclusions:Reasons for abstaining from marijuana have predictive utility in relation to later use, but these associations differ between those with and without prior marijuana use. Understanding the underlying reasons for stopping marijuana use or maintaining abstinence may inform youth substance use prevention and intervention programs.