Globalisation, migration and super diversity have urged teachers to cultivate their intercultural competence so as to work more successfully in their culturally diverse schools. Previous literature argues that teacher professional development for building intercultural competence plays a pivotal role in improving the intercultural school. For teacher professional development programmes to contribute to the improvement of the intercultural school, we should pay attention to their theoretical framework, content, and format. However, there is a shortage of literature and research that engages in in-depth descriptions of specific teacher professional development courses with an intercultural orientation. In order to bridge this gap, in this paper we critically discuss on a participatory course on stereotypes that we have developed and implemented in Greece aiming to promote teachers' intercultural development. What stems from our project is that it is only through participatory, collaborative, critical and action-research models of professional development that we may achieve change in teachers' attitudes and practices, and, in turn, facilitate school improvement.