loading . . . An Ecological Momentary Assessment Protocol to Measure Stress, Socialization, and Other Contributors to Smoking Behaviors Among LGBTQ+ Adolescents: Multimethod Evaluation of #feasibility, Acceptability, and Appropriateness From the Puff Break Research Study Background: Smartphone-based ecological momentary assessment (EMA) methods highlight the impact of minority stress and socialization (eg, discrimination, social support) on smoking behaviors in LGBTQ+ adults, however studies among LGBTQ+ adolescents are limited. The Puff Break EMA protocol was developed to address this gap. Objective: The purpose of this study is to report on the acceptability, #feasibility, and appropriateness of the Puff Break EMA protocol. Methods: We utilized a multi-method design to evaluate the acceptability, #feasibility and appropriateness of the Puff Break EMA protocol. Participants who reported tobacco/nicotine or cannabis product use within the last 30 days engaged in a two-week EMA trial, receiving five daily assessments measuring tobacco, nicotine and cannabis use, stress and socialization, and product craving. Post trial, participants completed a 15-minute exit survey and 60 minute semi-structured exit interview. The exit survey utilized the 12-item Weiner (2017) Acceptability, Appropriateness, and #feasibility measures and 6-item Mobile Application Rating Scale (MARS), App Specific Subscale and also included 7 open-ended responses. The exit interview focused on a review of participantâs data to help understand smoking patterns and experiences with the Puff Break EMA protocol along with questions guided by the Reach, Effectiveness, Adoption, Implementation, and Maintenance framework to understand how a future EMA mobile intervention aimed at monitoring and reducing tobacco, nicotine, and cannabis product use could effectively be disseminated to, accessed by, and implemented with LGBTQ+ adolescents. Lastly, lessons learned were obtained through feedback and data collected throughout the study. Results: Fifty adolescents between the ages of 15-19 (M=17.82, SD=1.19) were enrolled in the study August 2023 and July 2024. Participants predominantly reported using vaporized tobacco and nicotine products (94.0%), followed by cannabis products (78%). The study sample was diverse regarding sexual orientation and gender identities with 32% identifying as gay or lesbian, 32% bisexual or pansexual, and 14% transgender (neither transmasculine nor transfeminine). The median EMA response rate was 75%. Results indicated high #feasibility (M=4.43), acceptability (M=4.15), and appropriateness (M=4.46), of the Puff Break EMA protocol. The MARS subscale also indicated high acceptability and #feasibility for the EMA method to increase knowledge, awareness, and intentions to monitor tobacco/nicotine use (M=4.14). Triangulated results from closed and open-ended survey responses identified 5 key themes related to #feasibility, acceptability, and appropriateness. Participants highlighted the ease of the Puff Break EMA protocol, prompt survey reminders, and increased product use awareness. Key feedback from exit interviews included increased flexibility for survey timing, better response-option alignment, and appropriate only for populations interested in monitoring or reducing their product use. Conclusions: Findings indicate that using EMA methods to understand the impact of stress and socialization experiences on smoking behaviors in LGBTQ+ adolescents are feasible, appropriate, and acceptable. Clinical Trial: Not Applicable http://dlvr.it/TQTpfR