This paper presents new evidence on how enrollment expansion affects higher education access and production with a focus on social inequality and institutional stratification. From 1999 to 2012, the world's largest higher education expansion happened in China that annual college enrollment dramatically increased from 1,083,600 to 6,888,300. We evaluate this exogenous, unprecedented policy using nationally representative student-level survey data and newly available confidential institution-level data. Enrollment expansion, which reduced per-student resources, negatively impacted college quality as measured by value-added on graduates' employment and earnings. The inequality in access between high- and low-SES students and the stratified production between college institutional tiers persisted during expansion.