Recent legislative developments have contributed to the transformation of professional practices, forcing public organizations to diversify their resources. New public management principles raise a series of uncertainties related to the pursuit of conflicting objectives. Which behavioral practices of public management best fit with objectives of general interest ? Are the ongoing changes in the political and legislative context reflecting these directions ? While professionals are looking for new organizational benchmarks, the tensions inherent to the integration of multiple rationalities reveal serious difficulties in reconciling the mission of general interest with the functioning of the public service. An exploratory approach conducted with five museums of France underlines of the uncertainties experienced by professionals. A cross-cutting reflection on health professionals at the public hospital, under the influence of a logic budgetary rigor and rationalisation of the adminsitrative activity renews the interrogation on the various practives professionals in public management.