Retaining nurses is a crucial issue for psychiatric hospitals. While many psychiatric nurses are retiring, these services are considered unattractive by young graduates who prefer technical acts. In addition to these recruitment difficulties, young nurses are highly unstable. The question of the transmission of knowledge and skills in the services appears to be a determining factor. How can we meet the challenge of the transition between generations of nurses? In order to answer this question, the determinants of the intention of nurses to leave are presented. In addition, the mechanism of these determinants, identified during a research-intervention for French nurses practicing in psychiatry, is described. These elements are levers for action to be implemented.