There exists a large output of empirical research and numerous calls for reform in medical education (Cooke et al., 2010;Frenk et al., 2010). Relatively little of this research, however, to the best of our knowledge, focuses on the professional learning practices within medical education, particularly within the context of post-graduate medical education or PGME (Van de Wiel, et al., 2011;Van der Zwet et al., 2011). To this end, it is important that medical educators, administrators, and practicing Attending physicians are provided with a clear understanding of the professional learning environment of current medical Residents, the teaching methods used by Attending physicians and ultimately, the unique milestones, instances of critical learning, and the transitions within the learning process of specializing within a particular medical residency. The rationale, therefore, for this study was to attempt to fulfil some of the calls for further investigation into PGME in a gainful attempt to This thesis provides novel insight into how 'learning to become' occurs within PGME and specifically, within the context of emergency medicine. Due to the large volume of data gathered during the interview and observation process, the findings of this study were divided by focusing one chapter on the Residents (chapter 4) and the subsequent chapter focused on the Attending physicians (chapter 5). For the Residents, the nature of their learning was iii characterized by a struggle for autonomy while establishing an identity as a physician.Findings from the Residents also focused on how they managed themselves within the residency process by handling multiple relationships, learning from mistakes and debriefing, engaged in informal teaching, utilized technology, and were involved with transitions as impactful learning experiences during residency.Findings from the Attending physicians suggest that the residency process was an opportunity to specialize within a chosen field of practice while being able to consolidate knowledge and work in a clinical environment. The findings from the Attending physicians, moreover, suggest that impactful learning is often facilitated by 'important others' who are often involved with teaching and mentoring. Perspectives are also shared on the use of media and technology in practice. Lastly, the Attending physicians describe transitions as impactful learning experiences, particularly as they exited residency and practiced as fully qualified practitioners.Revisiting the research questions, the lived experience of the participants can be summarized into four major discussion points; 1) learning in emergency medicine involves dynamic changes in identity, 2) learning experiences are highly structured, but are informal in practice, 3) mentorship is critical in medical residency, and 4) instances of critical learning are varied and personal. The implications of the participants lived experience 'learning to become' practicing emergency physicians, led to both pedagogical and methodological recommen...