The COVID-19 pandemic represents a consequential moment of disruption for medical training that has far-reaching implications for professional identity formation (PIF). To date, this has not been studied. As medical education grapples with a postpandemic era, it is essential to gain insight into how the pandemic has influenced PIF to better support its positive influences and mitigate its more detrimental effects. This study examined how PIF occurred during the COVID-19 pandemic to better adapt future medical training. Constructivist grounded theory guided the iterative data collection and analyses. The authors conducted semistructured group interviews with 24 Ontario internal medicine residents in postgraduate years (PGYs) 1 to 3 between November 2020 and July 2021. Participants were asked to reflect on their day-to-day clinical and learning experiences during the pandemic. Twenty-four internal medicine residents were interviewed (12 PGY-1 [50.0%], 9 PGY-2 [37.5%], and 3 PGY-3 [12.5%]). Participants described how navigating patient care and residency training through the pandemic consistently drew their attention to various system problems. How participants responded to these problems was shaped by an interplay among their personal values, their level of personal wellness or burnout, self-efficacy, institutional values, and the values of their supervisors and work community. As they were influenced by these factors, some were led toward acting on the problem(s) they identified, whereas others had a sense of resignation and deferred action. These interactions were evident in participants' experiences with communication, advocacy, and learning. Residents' professional identities are continuously shaped by how they perceive, reconcile, and address various challenges. As residents navigate tensions between personally held values and apparent system values, individuals in supervisory positions should be mindful of their influence as role models who empower values and practices that are recognized by participants to be important aspects of physician identity.