PROJECT SUMMARY/ABSTRACT Nicotine vaping among adolescents has surged in prevalence over the past decade. Vaping poses clear health risks, is highly addictive, and leads to the use of combustible cigarettes. Our multi-disciplinary team, which includes expertise in youth participatory approaches, substance use prevention, nicotine use and cessation, and statistics, has developed an innovative school-based approach that promotes positive health behavior while also addressing academic standards, and thus incorporates both the academic mission of schools and youth health. YES-CAN! (Youth Engaged Strategies to Change Adolescent Norms) integrates the following evidence-based strategies: youth-adult collaboration; youth-developed narrative videos to convey health messages; peer leaders as change agents; and sustained implementation to change the normative environment. It rests on evidence that adolescents are more likely to change attitudes, norms, and behaviors when exposed to messages developed and delivered by peer role models rather than teachers, parents, or other adults. For this pilot/feasibility study, two middle/high school communities will receive the intervention. In each school community, we will implement a credit-earning high school class in which a trained teacher will deliver the one-year classroom-based program to 25-30 high school students, who will produce 6-8 short videos intended to increase refusal skills; promote stress management and positive coping; change social norms; prevent vaping initiation; and promote vaping cessation among current users. Videos will use a narrative approach and integrate known determinants of vaping. High school students will collaborate with the teacher and researchers to develop discussion guides and skills-building activities based on best practices for substance use prevention. In 6-8 eight sessions, high school students will deliver their videos to all students in the associated middle school. A text messaging component will reinforce and boost the effectiveness of the classroom sessions. Our overarching hypothesis is that this intensive approach that involves both middle and high school students in the same community will result in a new normative environment and a reduction in youth vaping. Aims for this pilot/feasibility study are to: 1) Determine the feasibility and acceptability of implementing the YES-CAN! program; and 2) Determine the feasibility and acceptability of the research protocols that will be used in a future efficacy trial. Primary efficacy outcomes include vaping ever use, past month use, daily use, susceptibility, behavioral intentions, and vaping-related knowledge, attitudes, perceived norms, resistance skills, and self-efficacy. Additionally, for high school students who participate in the intervention development and delivery, outcomes include positive youth development. Outcomes will be measured over a 13 month period.