PROJECT SUMMARY. Sexual and gender minority (SGM) youth, inclusive of lesbian, gay, bisexual, transgender, and queer individuals, are more likely to initiate ENDS use (or vaping) and to currently vape than non-SGM youth. The parent R01 of this proposed supplement Project SMART (Social Media Anti-Vaping Messages to Reduce ENDS Use Among Sexual and Gender Minority Teens; R01DA054236-01) is to evaluate the effectiveness of an SGM-tailored social media intervention to prevent vaping initiation among SGM youth ages 13-18 years. Scientific Rationale: The reach of evidence-based SGM-targeted tobacco prevention interventions is often inadequate due to barriers that limit the outreach, implementation, and maintenance of these programs. There is a critical gap in stakeholder engagement to narrow the research-practice gap such vaping prevention interventions developed for SGM youth are appropriate for real-world practice settings and meet the needs of future adopters. Objectives: The primary objective of this supplement in response to NOT- OD-22-032 is develop a multifaceted implementation strategy that can be utilized by potential implementers of the anti-vaping campaign intervention among SGM youth we are developing in Project SMART. The long term goal is to increase the reach, adoption, implementation and maintenance of the anti-vaping social media intervention to prevent vaping among SGM youth. Specific Aims: 1) Describe the implementation barriers, facilitators, and needs among future adopters and implementers of an anti-vaping social media campaign for SGM youth, 2) Identify the determinants that would make the campaign more likely to be adopted, implemented and maintained, 3) Use the data collected to inform a set of implementation strategies that are both feasible and acceptable to best meet the specific needs and contexts of each future adopters and implementer. Research Strategy: For this study, we will tailor Fernandez and colleagues' (2019) Implementation Mapping approach and: 1) conduct an implementation needs assessment among program implementers of the anti-vaping social media intervention, 2) determine the program implementation outcomes, performance objectives, determinants, and matrices of change objectives with program implementers (e.g., identifying what are facilitators and barriers to conduct the anti-vaping social media campaign), and 3) select theoretical methods and design implementation strategies. Participants will be 10-12 potential program implementers who will have a high level view of the context in which the anti-vaping social media campaign for SGM youth could be integrated within their health promotion efforts across diverse organization type, sector, and geographic region (e.g., national, state and local health agencies, professional groups, SGM youth community centers). Impact: This completion of this supplement research will lead to a theory and practice- informed implementation protocol to enhance the reach, adoption, i...