In this talk, we will share early findings from an NSF study of 75 doctoral students and recent PhDs in mathematics from underrepresented groups. The project has conducted in-depth, semi-structured interviews with four cohorts: newly accepted students, early graduate students (pre-qualifying exams), advanced graduate students (dissertation level), and recent PhDs (0-5 years since graduation).  The research questions in the study are: (1) What are lived experiences of successful underrepresented students who are pursuing mathematics PhDs? and (2) What formal and informal structures are perceived by doctoral students as effective supports? Themes drawn from the interviews can inform department policies and practices to create environments that support students from underrepresented groups as they earn PhDs in mathematics.