One of the pressing challenges for mathematics teacher educators is to identify the language, concepts, principles, and practices that can be the shared basis of professional dialog. Of course, in seeking commonalties in professional knowledge, educators of mathematics teachers have a substantial challenge. This challenge is compounded in that virtually all of the issues of interest to teacher of educators. ICME 9 saw active discussions on curriculum processes, mathematical topics, mathematical thinking and creativity, perspectives, on what constitutes knowledge, the role of technology in learning and doing mathematics, social and political factors, equity, and assessment of learning. These topics are all of interest to teacher educators and teachers alike. There are, nevertheless, topics of particular interest to teacher educators. WGA 7 sought to provide a forum for discussion and elaboration of these.