This paper explores school leaders' and teachers' ideas about drivers of improvement at local level in the decentralised Swedish school system. An institutional perspective is applied to investigate how institutional logics at macro level are played out at micro level in improvement processes. The paper draws on a three-year collaborative research project between a research team at a Swedish university and a municipality. Data emanate from interviews with 40 school leaders and 495 teachers in schools and preschools. The findings provide in-depth descriptions of how ideas based in coexisting logics generate tension and support in the organisations and thus provide an important contribution to our understanding of change processes in schools and preschools, and the challenges that accompany these processes.