Developing a Telehealth + mHealth Cannabis Use Intervention for Young Adults (MOMENT-V) - Daily cannabis use among young adults aged 18-26 years is at historically high levels and >4.8 million young adults meet criteria for cannabis use disorder (CUD). Heavy cannabis exposure during brain development adversely affects cognition, emotions, risk for psychiatric disorders, and educational and other social outcomes. However, most young adults with CUD do not receive treatment. Brief motivational interventions may be effective for CUD in young adults, but effects are small and evidence is of low quality. Combining motivational interventions with other approaches may enhance effectiveness, and provision in primary care and use of telehealth may improve reach. We have developed a novel intervention, MOMENT-V, that combines telehealth motivational enhancement therapy (MET) with mobile health (mHealth) ecological momentary intervention (EMI) to provide a fully remote brief intervention for CUD in young adults seen in primary care, building on our prior research on cannabis use in daily life, a brief intervention with in-person MET plus EMI, adapting in-person counseling for the virtual environment, and brief interventions in primary care. In an open pilot, 100% of young adults were retained, and satisfaction and engagement with MOMENT-V was high. We now propose a pilot randomized controlled trial of MOMENT-V vs. enhanced usual care in 60 young adults aged 18-26 years with CUD recruited from primary care clinics, using mixed methods and with follow-up at 3 weeks, 3 months, and 6 months. The specific aims are to determine 1) intervention feasibility (primary outcomes: intervention completion, EMI engagement, acceptability), 2) trial feasibility (primary outcomes: screening, eligibility, enrollment, retention), and 3) preliminary efficacy (primary outcomes: cannabis use frequency, problems from/negative consequences of cannabis use). Primary outcomes will be evaluated against a priori benchmarks. Secondary outcomes will include MET adherence to motivational interviewing principles, therapeutic alliance, duration of study activities, barriers, facilitators, CUD symptoms, amount of delta-9-tetrahydrocannabinol (THC) used in standard units, motivation to change use, psychological distress, cognitive function, and quality of life. All intervention and trial procedures will be conducted remotely. Additionally, we will explore the feasibility of videorecorded and live video-observed oral fluid testing for THC and of using these results to assess cannabis reduction in a fully remote trial. This proposal is responsive to PAR-22-183 areas of special interest, including research that uses innovative technologies and Stage I treatment development research testing behavioral interventions within primary care. Results will be used to develop an R01 proposal for a fully powered randomized controlled trial to test the effectiveness of MOMENT-V. Findings from the proposed study will enhance efforts to provide high-quality brief treatment to young adults with CUD and inform research using telehealth, mHealth, remote trial implementation, and oral fluid testing to objectively assess cannabis use reduction.