This article presents the extended workshop, a national professional development programme that was used in the preparatory stages of the introduction of a new mathematics curriculum for basic education (grades 1-9) in Portugal. These workshops are based on five major ideas-orientation towards practice, focus on students' learning, collaboration, practitioner research, and change of professional culture. The evaluation shows that these workshops constituted a stimulating professional development setting that encouraged teachers to reflect about classroom practice and students' learning and was quite successful in supporting an overall movement favourable to the orientations of the new curriculum.