Purpose Professional identity formation (PIF) can be defined as the integration of the knowledge, skills, values, and behaviors of a profession with one's preexisting identity and values. Several different, and sometimes conflicting, conceptualizations and theories about PIF populate the literature; applying these different theories in PIF curricula and pedagogic strategies can profoundly impact the PIF of future physicians. The authors conducted a critical review of the recent literature on PIF interventions in medical education to explore the conceptualizations of and theoretical approaches to PIF that underlie them. Method The authors searched articles on PIF educational interventions published in 5 major medical education journals between 2010 and March 2021. The articles' context and findings were extracted, analyzed, and summarized to identify conceptualizations and theoretical approaches to PIF. Results The authors identified 43 studies examining medical education interventions aimed at influencing PIF. The majority of the studies (n = 31) focused on undergraduate medical education. Reflective writing and the use of narrative reflections were the dominant modes of student activity in PIF interventions, supporting the dominant individualist approach to PIF. Less commonly PIF was understood as a socialization process or as an active process with both individually and socially focused influences. Conclusions Relying on reflective writing as the intervention of choice to impact PIF feeds the dominant individualist perspective on PIF. An unintended consequence of this individualist orientation is that cultural problems embedded in the profession can become burdens for individual physicians to personally bear. Future education and research into PIF should account for theoretical preferences and the impact of these preferences.