Context: Professional identity development in professional master's (PM) athletic training students occurs over time and is influenced by numerous socializing factors. Although socialization processes of athletic training students have been examined, professional identity development related to the Weidman et al graduate and professional student socialization framework [Weidman JC, Twale DJ, Stein EL, et al. "Socialization of Graduate and Professional Students in Higher Education: A Perilous Passage?" ASHE-ERIC higher education report. Vol 28, No. 3. Jossey-Bass Higher and Adult Education Series; 2001] has never been examined in athletic training. This model values the multiple networks, individuals, and experiences that influence graduate students throughout their program. Objective: To assess the lived experiences of 1 cohort of students enrolled in a PM athletic training program and determine what curricular and clinical education factors influence the development of professional identity. Design: Qualitative study. Setting: Focus group interview. Patients or Other Participants: Ten of 12 (83%) students (5 females and 5 males) from a single PM athletic training cohort program participated. Data Collection and Analysis: We conducted a focus group interview, which we transcribed verbatim, with participants during the last week of their last semester in the PM athletic training program. Data analysis was deductive and then inductive throughout the coding process, and we reached data saturation at the individual participant and cohort levels. We ensured trustworthiness through multiple analyst triangulation, peer expert review, and multiple data sources. Results: Three factors influenced the development of the PM athletic training student's professional identity: (1) their clinical education experiences, (2) the cohort experience, and (3) their school/life balance. Within the clinical education experience, the immersive experience, clinical setting, and patients and preceptors were also influential. Conclusions: This study used the Weidman et al socialization model. The experiences of PM athletic training students and their professional identity development are inclusive of the relationship with others throughout the educational experience, as well as their self-reflective practices within the field. It is important for stakeholders to understand the many factors that influence professional identity development.