This paper describes part of research conducted with fifteen Numeracy Coaches as they carried out their work supporting teachers in Victorian government schools. There was great variation in the mathematical background of coaches, and this area of the research investigated the changing perception of professional learning priorities to support their work in schools, using questionnaire and interview data. The data indicated that the coaches' priority for mathematics content knowledge and pedagogical content knowledge strengthened over the year of the study. (Contains 3 tables.) [For the complete proceedings, "Shaping the Future of Mathematics Education. Proceedings of the Annual Conference of the Mathematics Education Research Group of Australasia (33rd, Freemantle, Western Australia, Australia, July 3-7, 2010)," see ED520764.]