Purpose. Peer crowd-targeted campaigns are a novel approach to engage high-risk young adults in tobacco use prevention and cessation. We elicited the perspectives of young adult key informants to understand how and why two social branding interventions were effective: (1) "COMMUNE," designed for "Hipsters" as a movement of artists and musicians against Big Tobacco, and (2) "HAVOC," designed for "Partiers" as an exclusive, smoke-free clubbing experience. Design. Qualitative study (27 semistructured qualitative phone interviews). Setting. Intervention events held in bars in multiple U.S. cities. Participants: Twenty-seven key informants involved in COMMUNE or HAVOC as organizers (e.g., musicians, event coordinators) or event attendees. Measures. We conducted semistructured, in-depth interviews. Participants described intervention events and features that worked or did not work well. Analysis. We used an inductive-deductive approach to thematically code interview transcripts, integrating concepts from intervention design literature and emergent themes. Results: Participants emphasized the importance of fun, interactive, social environments that encouraged a sense of belonging. Anti-tobacco messaging was subtle and nonjudgmental and resonated with their interests, values, and aesthetics. Young adults who represented the intervention were admired and influential among peers, and intervention promotional materials encouraged brand recognition and social status. Conclusion. Anti-tobacco interventions for high-risk young adults should encourage fun experiences; resonate with their interests, values, and aesthetics; and use subtle, nonjudgmental messaging
