The challenge of educational improvement, due mainly to the complexity of educational systems, is well-known. The aim of this study is to provide knowledge regarding the process of change within schools to better understand how it might depend on cultural context and the characteristics of individual schools. Based on interventions in four compulsory schools (6-15 years old students) in Iceland, the study uses both qualitative and quantitative data. The process of change was guided by a framework grounded in professional learning community principles and designed to be adaptive for cultural contexts as well as the interdependence of different factors of educational systems. Theories of drivers of change and indicators of schools as professional learning communities were used to understand cultural conditions within them. The main findings indicate that the change process in "team-driven" schools with relatively high levels of teacher collaboration and engagement works well in the framework. By contrast, the change process seemed restrained in the "profession-driven" and "problem-driven" schools characterised by either a high level of teacher autonomy and lack of collaboration or engagement in solving several generic problems. The study provided valuable insights regarding the complexity of facilitating change, particularly, the importance of identifying main drivers of change affecting an intervention process at the initiation stage.