We investigate institutional change as the co-occurrence of deinstitutionalization and institutionalization, while accounting for its determinants at multiple levels of analysis to further our understanding of how individual characteristics aggregated at the organizational level and organizational characteristics together account for the erosion and emergence of practices within the field. We empirically explore this question in a multi-level dataset of UK law firms and their employees, looking in particular at how the practice of equity partnership faded away and how non-equity partnership emerged as a new practice. Our results contribute to the literature on institutional change and the micro-foundation of institutions.