Proposals to implement fatigue-management strategies in residency education assume that medicine shares the view of other risk-adverse industries that fatigue is hazardous. This view is an essential underpinning of fatigue-management strategies that other industries have embedded as part of their workplace occupational health and safety programs. We sought to explore how residents understand fatigue in the context of their training environment.We interviewed 21 residents in 7 surgical and nonsurgical programs at Western University in 2014. All participants met the inclusion criteria of routinely working 24-hour call shifts while enrolled in their training program. Data collection and analysis occurred iteratively in keeping with constructivist grounded theory methodology and informed theoretical sampling to sufficiency.Four predominant principles of fatigue captured how the social learning environment shaped residents' perceptions of fatigue. These included the conceptualization of fatigue as (a) inescapable and therefore accepted, (b) manageable through experience, (c) necessary for future practice and (d) surmountable when required.This study elaborates our understanding of how principles of fatigue are constructed and reinforced by the training environment. Whereas fatigue is seen as a collective hazard in other industries, our data showed that, in residency training, fatigue may be seen as a personal challenge. Consequently, fatigue-management strategies that conceptualize fatigue as an occupational threat may have a limited impact on resident behaviour and patient safety.