Most adult smokers initiate tobacco use before age 18, with considerable increases in initiation and the highest rates of use observed between the ages of 18 and 29. Although conventional cigarette use is declining somewhat, use of e-cigarettes that can promote future nicotine addiction is on the rise, particularly for youth. These statistics speak to the need to identify new methods of delivering messages designed to reduce both cigarette and e-cigarette (e-cig) use to younger Americans (i.e., adolescents and young adults). One promising approach involves delivery of graphic health warnings that communicate the risks associated with these products. The proposed research explores delivery of graphic health warnings from within virtual gaming environments. Previous research indicates that videogames can be used effectively to deliver smoking- prevention messages, but past efforts have focused on videogames designed around health-education themes (what are called “serious” games). With surveys indicating that 97% of adolescents and 80% of young adults play videogames for entertainment, use of entertainment videogames as a tool for delivering graphic warnings has tremendous potential to influence youth cigarette and e-cig rates. However, before such an approach can be pursued, researchers need to better understand health communication dynamics in computer-mediated, virtual gaming worlds. The current project addresses this need and tests the viability of The Virtual Transportation Model of Health Communication. This model posits that, as gamers become psychologically immersed (or “transported”) into virtual reality, their tendency to resist persuasive messages they encounter in these worlds is disrupted. The model further posits that such disruption will typically be strongest among individuals who are most likely to resist or reject “real-world” interventions. Support for predictions comes from pilot research conducted by our research team. In this research, graphic health warnings against alcohol- impaired driving and cigarette smoking were embedded in background scenes of entertaining, interactive 3D virtual gaming worlds. Such messages were shown to reduce willingness to engage in these behaviors in the future, particularly among higher-risk individuals who reported feeling psychologically “transported” during game play. The proposed research will build on this work by testing the viability of videogame-based interventions. In Phase 1 (Years 1 & 2) we will refine two existing videogames and develop two new ones while simultaneously empirically evaluating the best methods of delivering in-game health communications and the mechanisms by which transportation heightens in-game influence. In Phase 2 (Years 3 & 4), we will conduct randomized field trials of game-based interventions with two groups, a probability sample of adolescents (13 – 18) and an at-risk sample of young adults (18 – 24). In Phase 3 (Year 5) we will aggregate data across studies to...