PROJECT SUMMARY/ABSTRACT Negative influence from peers and friends is a well-known potent predictor of adolescent smoking initiation. However, what is not known is how to design and implement an intervention that promotes positive social influence for adolescents (i.e., connection with and support from others who do not intent to use tobacco). One example of an intervention that lacks positive social influence is a Web-based, computer-tailored intervention called A Smoking Prevention Interactive Experience (ASPIRE). ASPIRE includes videos and activities with messages that successfully provide adolescents individually with information on smoking risks, using human- computer interaction. Still, for better outcomes, it can benefit from positive social influence through peer-to- peer interaction. The long-term research goal is to develop, implement, and evaluate social influence and behavioral interventions that can be applied to prevent the use of tobacco products among adolescents. One innovative approach to fill the gap is to apply social influence strategies. First, game-based social activities (GSAs) can facilitate exploration of health information and drive social discussions against tobacco use. Second, social network analysis allows us to strategically group at-risk adolescents (i.e., those who intend to use tobacco), with close peers who do not intend to use tobacco (i.e., change agents), as they engage in ASPIRE. Change agents will positively influence at-risk adolescents for two reasons: (1) At-risk adolescents will be dominated in number by change agents, and (2) their interaction with change agents will be directed by the healthy content of ASPIRE and the GSAs. The objective of the funded R00 research is to identify the effect of ASPIRE on key mechanisms underlying adolescents’ intention to use tobacco products (cigarettes, cigars, hookah water pipes, and vaping products), when social influence strategies are added to the intervention. The objective of the current administrative supplement through the 2021 NIDA Summer Research Internship Program is to support the research training of an undergraduate student from an underrepresented group with a meaningful substance abuse and addiction research experience in adolescent tobacco prevention and cessation. With mentorship from the PI (Georges Khalil, MPH, PhD) and a Graduate Student Research Assistant (David McLean, MA), the intern will receive training in (1) health communication strategies for adolescent tobacco prevention and cessation, (2) implementation of community based randomized trials for behavioral interventions, and (3) mixed-method data analysis skills. Ultimately, the research plan for this project will provide a healthy training environment for the intern to obtain skills in substance abuse prevention research through behavioral science.