Although schools are usually regarded as important agents for social inclusion, research has shown that they may also function as agents of exclusion itself. The goal of this paper is to deepen our understanding of how schools function as agents of exclusion and how they can become more effective agents of inclusion. It is based on action research carried out with the "New Education Environment", a programme aimed at helping secondary schools in Israel work more effectively with "at-risk" pupils. This research led to the discovery of a self-reinforcing "cycle of exclusion" that involves both pupils and staff in these schools and "frames" of thinking and action that keep it in place. This paper also describes the cycle of exclusion and its frames as well as an alternative frame that has been used to help school staff to step out of the cycle of exclusion and act more effectively to foster inclusion.