ABSTRACT Cannabis is a widely used psychoactive substance among young adults (YAs), with ~44% using in the past year. Daily use by YAs not attending college (14.5%) is 3x the prevalence of daily use by college attending peers (4.7%). Cannabis is associated with acute and longer-term consequences. A growing concern among researchers and clinicians is of frequent and/or high-intensity use (i.e., daily/near daily use, use multiple times a day, and use of higher potency THC products). Although published research has grown exponentially in the last decade regarding correlates and consequences of cannabis, development and evaluation of efficacious brief interventions to reduce cannabis use is still needed. Mobile health (mHealth) technology may help address gaps between clinical need and formal clinical services, particularly for non-treatment seeking YAs and those typically underserved and underrepresented in research such as non-college YAs. The proposed R34 application uses a multi-method user-informed approach to develop a novel brief motivational mHealth intervention that incorporates cutting-edge cannabis intervention research. The proposed intervention is an integrated mobile-enhanced web-based program with subsequent text messages for 5 weeks that provides reflection on YAs’ cannabis use in 5 domains: (1) patterns/potency of use, (2) motivations for use, (3) social connections and use, (4) personal use goals and use and (5) protective behavioral strategies. The intervention prioritizes autonomy and will allow YAs to direct their journey through the program and allowing for self- identification of personal reduction goals. YAs are at different places with respect to readiness to change, thus by allowing the YA to direct their journey, the program will present appropriate content based on their interests and tailored to their self-efficacy and readiness to change. YAs will have opportunity to reflect on motivations for using cannabis, and when appropriate, cognitive behavioral skills-training for substance-free strategies for coping with negative mood and emotions, potential for engaging in substance-free activities, social skill building, exploration of the relationships among values, future goals, and cannabis use, and opportunities to explore lower-risk use. Aim 1: Develop a YA cannabis intervention (Take 5) to reduce cannabis use and negative consequences among non-collegiate YAs engaging in frequent/high-intensity cannabis use. Focus groups and user experience interviews will inform the development of the intervention. Aim 2: Conduct a 6- month pilot study with non-collegiate YAs in WA (who use cannabis 15+ days/month, use 2+ times per day when use, or use high-potency THC products [60%+]) to determine feasibility and acceptability. 120 YAs will be randomized to Take 5 (n=60) or attention control condition (n=60). The present application addresses several priorities in NIDA’s Strategic Plan, including using technology (e.g., smartphones) to ...