PROJECT SUMMARY/ABSTRACT Marijuana (MJ) use is prevalent among young adults (YAs) and has remained stable or slightly increased (Schulenberg et al., 2019), while MJ use disorders have risen considerably (Hasin et al., 2015). MJ use has been linked to consequences, including motor vehicle accidents (Volkow et al., 2014). Self-regulation processes are central to substance use behaviors. Some YAs may intend to reduce their use on certain days but almost never manage to do so, while other YAs may intend to reduce their use and are generally successful. The circumstances under which YAs may limit their marijuana use or consequences in response to changes in psychological states and contextual factors is not well understood. This application addresses this gap by elucidating the extent to which YAs engage in MJ-specific self-regulation processes in their everyday behavior and their natural environment and will identify psychological and contextual factors associated with variability in MJ-specific self-regulation both across days and throughout the day. This project will recruit a community sample of YAs ages 18-29 years (N = 200), who use MJ regularly (15 or more days in the past month). YAs may regulate or limit their MJ use or consequences in a variety of ways, such as using smaller quantities on a given day to minimize interference with other responsibilities. Accordingly, self-regulation is best viewed as a dynamic process that varies both across days and throughout the day. Psychological (e.g., craving, anxiety, depression) and contextual (e.g., alcohol and tobacco use) factors may partly explain when YAs are more or less likely to limit their MJ use or consequences. Craving and social anxiety have been linked to MJ use among college students using daily survey designs (Buckner et al., 2012a, 2012b; Phillips et al., 2015). MJ use and/or consequences among YAs have also been associated with depressive symptoms and anxiety, although associations may be more pronounced among females (Buckner et al. 2007; Wright et al., 2016). This project uses a rigorous ecological momentary assessment (EMA) design in which YAs report on their behavior and related psychological and contextual factors 4x/day for two consecutive weeks (56 web- based surveys per person). The aims are to: (1) examine complex associations between MJ-specific self- regulation processes and MJ use/consequences both across days and throughout the day; (2) examine complex associations among psychological states (e.g., craving, anxiety) and contextual factors (e.g., alcohol and tobacco use) in relation to MJ-specific self-regulation and using more MJ than intended; and (3) evaluate between-person and daily-level moderators to determine for whom and when associations may be stronger. The knowledge gained can inform current self-regulation theories, be used in existing interventions to better support active change or discuss commonly encountered obstacles to limiting one’s MJ use, and be used ...