In the Île-de-France region, the retention of nurses is a crucial issue for psychiatric hospitals. While many nurses specializing in psychiatry are retiring, psychiatric services are considered unattractive by young nurses who prefer technical acts. In addition to these recruitment difficulties, there is a high level of instability among young nurses. How do we meet the challenge of managing the transition between generations of nurses? We used an action research methodology during which we led multidisciplinary work groups in two psychiatric hospitals in the Île-de-France region. By comparing the results of scientific research on the determinants of the intention to leave and the perceptions of the staff of the two establishments, we have drawn up a diagnosis that was co-constructed with the participants. Three categories of departure factors specific to these institutions were identified: increased workload, loss of meaning in care, transfer of skills and practices for integrating new nurses. We present the retention practices developed following this diagnosis and the difficulties encountered in the follow-up to the action research.