We sought to better understand what defines a critical incident experience for the surgical trainee. Critical incidents are formative moments stamped indelibly on one's memory that shape professional identity. The critical incident technique-using participants' narratives to identify patterns and learn from their perceptions-has been explored in some healthcare settings, but there has been no inquiry within surgery. Surgical residents at 5 residency programs (1 community, 1 university-affiliated, 3 university) were surveyed using an online questionnaire from November to December 2020. Convenience sampling was used to identify the study population. Participants were invited to write about formative, impactful experiences in training. Interpretive description was the qualitative methodology used to locate information, analyze, and record patterns in the data. Individual responses were categorized and assessed for overlying themes. Overall, 28 narratives were collected from surgery residents in 3 specialties (general surgery, plastic surgery, and urology), with postgraduate year representation of post-graduate years 1 to 6. Respondents were 40% female. Nineteen of the narratives reported a negative experience. Four themes were identified from responses: 1) growth through personal self-reflection, 2) difficult interpersonal interactions, 3) positive team dynamics as a psychological safety net, and 4) supportive program cultures that promote learning. Critical incident narratives among surgical residents indicate that unforgettable and formative experiences-both positive and negative- occur in 4 domains: within the individual, within a relationship, among a team, and within a program. Further exploring these domains in surgical training will inform optimal educational programming to support trainee development and wellbeing.