Objective: The study aimed to identify phases of bystander intervention (BI) for problematic alcohol use (PAU) among college students. Participants: Twenty focus groups and nine interviews were conducted. Methods: Transcripts were thematically analyzed. Results: The phases of the Bystander Intervention for Problematic Alcohol Use Model (BIPAUM) include: (1) plan in advance, (2) notice and interpret a sign, (3) decide (i.e., assume responsibility, assess support/feasibility to intervene, and identify intervention strategy), (4) intervene, and (5) assess outcomes. Assessing outcomes loops to influence future behavior and each phase is influenced by barriers and facilitators. Conclusions: These unique phases should be considered when designing and evaluating intervention programs for PAU to meet students' needs and better reduce PAU. Future research should empirically test the BIPAUM. The results of the current study demonstrate a promising opportunity for applying BI to PAU, with the goal of reducing risky drinking among college students.