Through this study, we sought to understand the determinants of the resilience of healthcare staff during the COVID-19 health crisis. Its goal was to gain a deep understanding of the motives, forces and processes at work in the complex dynamics of resilience. It seems all the more crucial to gain such understanding, given that there seem to be lessons to be learned for a rethinking of working conditions in public hospitals. In particular, during the current pandemic, the healthcare staff seem more than ever exposed to psychosocial risks and to a working life that has never been so stressful. The study was carried out among the healthcare staff at a public hospital in Tunisia, and its findings show that resilience results from the activation of predispositions, protective factors and resources that are as much personal as they are interpersonal and sociocultural. Resilience is not a spontaneous response in a work context marked by adversity and uncertainty. It results from a mix involving personal dispositions, group dynamics, social support, family stability, leadership style and situational contingencies. Our findings further show that resilience generates real added value for patients, for caregivers and for healthcare practice as much in human, healthcare and ethical terms as in economic terms. Developing resilience is a responsibility to be shared between healthcare staff, the hospital system, health authorities, managers and leaders of healthcare institutions.