The purpose of this report is to briefly present CERME’s Thematic Working Group (TWG) 20 on Mathematics Teacher Knowledge, Beliefs and Identity. At CERME13 (Hungary, 2023) this TWG was led by the authors, inheriting the legacy of more than thirty scholars in the field who have led the group since it started in 2013. We start by briefly outlining the history of CERME TWG20, then present the main topics and ideas addressed in the Group and conclude with some reflections on the future of the Group drawing on the synthesis that has emerged from previous conferences.