Given the need to improve mathematics education in the U.S. (National Research Council, 2013), calls have been made for doctoral programs to provide students with professional support in teaching preservice teachers (PSTs). Although progress has been made, many doctoral programs are not devoted to the professional development of their students as mathematics teacher educators (MTEs). Typically, doctoral students do not receive professional development with regards to teaching; and some do not have the opportunity to teach at all. In a survey of MTEs who had recently begun teaching at the university level, Yow et al. (2016) found that many did not feel prepared to do so and wished they had had more professional development opportunities to learn about teaching during their doctoral studies. Professional development, in general, is most effective when it is collaborative, continuous, school-based, and aimed at students' learning. These characteristics are embodied in the professional development model lesson study. Although lesson study has been used in a variety of settings, its use for developing doctoral students as MTEs has not been documented. Therefore, the purpose of this study was to examine the support that the lesson study process might provide for doctoral students teaching an elementary mathematics content course for PSTs.