PURPOSE: To develop a road map for educators attending to medical students' professionalism lapses, aiming to offer an empirical base for approaching students who display such lapses. METHOD: Between October 2016 and January 2018, 23 in-depth interviews with 19 expert faculty responsible for remediation from 13 U.S. medical schools were conducted about the way they handle students' professionalism lapses. Three researchers independently completed three rounds of coding. Data collection, coding, and analysis were performed in a constant comparative process. A constructivist grounded theory approach was used to develop an explanatory model for attending to students' professionalism lapses. RESULTS: Based on participants' descriptions, the authors developed a three-phase approach for attending to professionalism lapses. In phase 1, experts enacted the role of concerned teacher, exploring the lapse from the student's perspective. In phase 2, they functioned as supportive coach, providing feedback on professionalism values, improving skills, creating reflectiveness, and offering support. In phase 3, if the student did not demonstrate reflectiveness and improvement, and especially if (future) patient care was potentially compromised, participants assumed an opposite role: gatekeeper of the profession. CONCLUSIONS: An explanatory model for attending to professionalism lapses that fits in the overarching "communities of practice" framework was created. Whereas phase 1 and 2 aim at keeping students in the medical community, phase 3 aims at guiding students out. These findings provide empirical support to earlier descriptive, opinion-based models and may offer medical educators an empirical base for attending to students who display professionalism lapses.