Within the issue of the modernization of public administration, our initial focus is to question the existence of links between a reform within an administration and its organizational identities. Such changes doubtless entail a transform of many aspects of public administration, such as organisational methods, HRM policy, the approach to planning and fulfilling its tasks, structures, terms of reference etc. This transformation involves the upgrading of operational methods and different skills and values, and results in the disruption of the organisational identity and the professional identities of members of the organisation (Fu et al., 1999; Abrams & Hogg, 1987). From empirical data collected within a Belgian Ministry, we assume that the introduction of a New Public Management reform leads to a hybridization of identity logics within public administration, but in other respects, the reform process can eventually be influenced by the identity logics. Using a longitudinal qualitative analysis, we distinguish 7 identity profiles, characterised by their reference to an identity logic (public service, public managerialism or pragmatism) and their perception of the context (congruence or dissonance). Through our case study, our hypothesis of organizational identities and reform process co-structuring appears to be valid, as shown by the hybridization of identity logics within the Ministry. Our results allow us to assume a modification of identity points of reference following a reform, as well as a reinterpretation of this reform through the identity filter. Our longitudinal approach reveals the identity dynamics, by identifying notably the shift processes from one position to another, and leads us to propose a model of contextualized identity dynamics. We are also able to show which factors produce (or are likely to produce) identity shifts, and the frame of mind of each identity profile towards change (1) as it is experienced and (2) in a projective way. These results draw attention to a number of points which provide the basis of further work on their possible application in management. The factors influencing the shift from one identity profile to another are closely linked with the concept of motivation; many studies have demonstrated the linked between different forms of identification and the attitudes or behaviour of the members of an organisation. Several studies have in fact shown the effects of compatible identity (or identification), on the construction of organisational involvement showing how identification impacts on significant attitudes and behaviours in members of an organisation, such as turnover, satisfaction, involvement, cooperation, acceptance of change or internalisation (Foreman & Whetten, 2002; Ashforth & Mael, 1989; Dutton et al., 1994; Reger et al.,1994). Moreover, the diversity of identity profiles and the ways in which they change suggest that differentiated managerial approaches are required, following the idea that there is no single way of reducing dissonance and that the ways of tackling identity issues in a context of change vary from one profile to another. Finally, the interpretative approach proposed by our analytic model could serve as the basis for developing management tools for framing and accompany change processes within an organisation. REFERENCES Abrams, D.; Hogg, M.A. (1987) «Language, attitudes, frame of reference and social identity: a Scottish dimension» Journal of Language and Social Psychology, vol.6, n°3-4, pp.201-213. Ashforth, B.E.; Mael, F. (1989), "Social identity theory and the organization", Academy of Management Review, vol. 14, pp.10-39. Dutton, J.E.; Dukerich, J.M.; Harquail, C.V. (1994) "Organizational Image and Member Identification", Administrative Science Quarterly, vol.39, pp.517-554.