Sociological research has long been interested in inequalities generated by and within educational institutions. Although relatively rich as a literature, less analytic focus has centered on educational mobility and inequality experiences within graduate training specifically. In this article, we draw on a combination of survey and open-ended qualitative data from approximately 450 graduate students in the discipline of sociology to analyze graduate school pipeline divergences for first-generation and working-class students and the implications for inequalities in tangible resources, advising and support, and a sense of isolation. Our results point to an important connection between private undergraduate institutional enrollment and higher-status graduate program attendance--a pattern that undercuts social-class mobility in graduate training and creates notable precarities in debt, advising, and sense of belonging for first-generation and working-class graduate students. We conclude by discussing the unequal pathways revealed and their implications for merit and mobility, graduate training, and opportunity within our and other disciplines.