A controversial, equity-focused mathematics reform in the San Francisco Unified School District (SFUSD) featured delaying Algebra I until ninth grade for all students. This study examines student-level longitudinal data on mathematics course-taking across successive cohorts of SFUSD students who spanned the reform's implementation. We observe large changes in ninth and 10th grades (e.g., delaying Algebra I and geometry). Participation in Advanced Placement (AP) math initially fell 15% (6 percentage points), driven by declines in AP calculus and among Asian/Pacific Islander students. However, growing participation in acceleration options attenuated these reductions. Large ethnoracial gaps in advanced math course-taking remained.