This working group continues to develop a research program and scholarly inquiry focused on the study of mathematics teacher educators' (MTEs') practices and their impacts on preservice teachers (PSTs). The research agenda contains two strands of inquiry exploring (1) empirical links between PSTs’ development and MTEs’ practices and (2) variation in MTEs’ practices and the evolution of methods course activities over time. Participants will discuss and dissect (a) existing literature illuminating the impact of methods activities on PSTs’ development, (b) methods of documenting and exploring MTEs’ practices and (c) the next steps to be taken in the development of the research agenda and the design of scholarly inquiry. Dialogues and collaboration among working group members will be encouraged. We will provide opportunities for individuals or teams to engage in the development of facets of the emerging research agenda.