Abstract. Despite an abundance of studies on hybridization and hybrid forms of organizing, scholarly work has failed to distinguish consistently between specific types of hybridity. As a consequence, the analytical category has become blurred and lacks conceptual clarity. Our paper discusses hybridity as the simultaneous appearance of institutional logics in organizational contexts, and differentiates the parallel co-existence of logics from transitional combinations (eventually leading to the replacement of a logic) and more robust combinations in the form of layering and blending. While blending refers to hybridity as an 'amalgamate' with original components that are no longer discernible, the notion of layering conceptualizes hybridity in a way that the various elements, or clusters thereof, are added on top of, or alongside, each other, similar to sediment layers in geology. We illustrate and substantiate such conceptual differentiation with an empirical study of the dynamics of public sector reform. In more detail, we examine the parliamentary discourse around two major reforms of the Austrian Federal Budget Law in 1986 and in 2007/2009 in order to trace administrative (reform) paradigms. Each of the three identified paradigms manifests a specific field-level logic with implications for the state and its administration: bureaucracy in Weberian-style Public Administration, market-capitalism in New Public Management, and democracy in New Public Governance. We find no indication of a parallel co-existence or transitional combination of logics, but hybridity in the form of robust combinations. We explore how new ideas fundamentally build on -and are made resonant with -the central bureaucratic logic in a way that suggests layering rather than blending. The conceptual findings presented in our article have implications for the literature on institutional analysis and institutional hybridity.