A fundamental goal of medical education is the active, constructive, transformative process of professional identity formation (PIF). Medical educators are thus charged with designing standardized and personalized curricula for guiding, supporting, and challenging learners on the developmental professional identity pathway, including the process of socialization. The author of this Commentary provides an overview of foundational principles and key drivers of PIF supporting the being, relating, and doing the work of a compassionate and competent physician. Key elements of PIF including guided reflection, use of personal narratives, integral role of relationships and role modeling, and community of practice are viewed through various lenses of PIF theory and pedagogy. Questions informing the PIF discourse are raised, including interprofessional identity considerations. Central emergent themes of reflective practice, relationships, and resilience are described as supporting and reciprocally enhancing PIF. Overarching lessons include attending to learners' and faculty's PIF within a developmental trajectory of the professional life cycle; process and content within PIF curricula as well as learners' individual and collective voices; curricular/extracurricular factors contributing to socialization, self-awareness, development of core values, and moral leadership; integrating PIF domains within pedagogy; faculty development for skilled mentoring and reflective coaching; and implementing resilience-promoting skill sets as "protective" within PIF. Outcomes assessment including the impact of curricula on learners and on patient-centered care can be challenging, and potential next steps toward this goal are discussed.