This paper explores the ways in which collaborative action research can facilitate the development of inclusive practices and thinking in schools. The paper uses examples from a study that involved three countries and eight secondary schools to illustrate how the process of collaborative action research promoted inclusive thinking and practices. The study combined a well-established approach of professional development -- lesson study -- and a framework for engaging with the views of students. This led to a distinctive model of teacher professional development that has at its core the idea of engaging with the views of students. Thematic analysis of data collected from all the settings over three years, highlighted three ways in which collaborative action research led to the promotion of inclusive practices and thinking in schools: through teacher collaboration; through the development of reflective practice; and through student active participation. It is argued that what was distinctive through the process was the fact that collaboration occurred between adults and students, something that is less evident in the collaborative action research literature. Through this process, inclusive thinking and practices were developed.