This study describes preservice teachers' beliefs about teaching mathematics for social justice (TMSJ) after experiencing a two-part professional development (PD) workshop on the subject. The research question is: To what degree does a PD experience, designed by a preservice teacher, influence preservice teachers' beliefs about TMSJ? The lead author is a preservice teacher who designed and enacted two workshops for education majors at Midwest University. Results indicated that preservice teachers' beliefs were statistically significantly different, with their beliefs trending toward "more strongly agree" about TMSJ after the two-part PD. There was also less variance in their responses to the survey after the PD compared to before it. This research offers (a) a narrative of preservice teacher-driven PD and (b) a rich description of a PD for preservice teachers, thus adding to prior literature about in-service teachers' outcomes.