Introduction: project management is one of the proficiencies that head nurses are expected to have. Context: Work on the improvement of organizations carried out by head nurses is rarely covered in the literature. Objectives: to follow the implementation of actions from projects led by head nurses and to analyze the parameters of success. Method: for a year, an intervention study followed seventeen projects initiating improvement measures. Semi-structured interviews were conducted with healthcare teams and managers. All of them reported the results of the implementation of each measure as an operational improvement. A mixed analysis containing a logistic regression investigated associations between the result of the action and the various contextual characteristics. Results: this study involved 111 actions, of which 71% of them resulted in operational improvement. The organizational and supporting actions had a high success rate, which decreased when hazards were not managed by healthcare managers. Discussion: this study highlights the place of strategies in the implementing methods and the chosen actions. Recommendations are made in order to promote collective assessment. Conclusion: scientific approaches are proposed to discuss the organizational work of head nurses.