This thesis sought to analyze why the Homeland Security Enterprise HSE disregards practices that conform to the scientific understanding of human fatigue and to identify the effective human-error mitigation practices of two other high-consequence fields that may be useful to the HSE. Using the constant comparative method, the command center work environments of the HSE, nuclear power, and air traffic control were analyzed with regard to fatigue-mitigation practices and policies. Despite remarkable similarities in their public safety function and human-technology interface, the resulting grounded theory highlights key differences. In contrast to nuclear power and air traffic control, the HSE has yet to record a serious fatigue incident to serve as a catalyst for change, and unlike those two industries strong safety cultures, the HSE command centers continue to operate in a deeply rooted bravery culture that prevents the focus on fatigue issues. This thesis brings attention to a clear safety gap and makes practical recommendations that would facilitate the HSEs intentional movement toward a safety culture through the implementation of comprehensive fitness-for-duty programs, multilevel fatigue mitigation training, and the gathering and continual review of human-error data in its command-center work environments.