This is part of a larger ethnographical study concerning how school development in a local educational context sets cultural and social life in motion. The main data "in this article" consists of semi-structural interviews with teachers (facilitators) who have the responsibility of carrying out a project about formative assessment in upper secondary schools in the south of Sweden. The focus of the study is how the teachers make meaning of their position as facilitators and leaders, how they handle their fellow teachers' criticism and resistance, how power transforms professional and human relationships, and how complex and weakly articulated power results in conflicting and ambivalent possibilities for action. From our perspective, the resistance the facilitators meet, although the project makes use of a concept that has proved to be successful, reveals an ambivalent structure where the facilitators have to face contradictory demands from different stakeholders.