The fiscal and educational consequences of charter expansion for non-charter students are central issues in the debate over charter schools. Do charter schools drain resources and high-achieving peers from non-charter schools? This paper answers these questions using an empirical strategy that exploits a 2011 reform that lifted caps on charter schools for underperforming districts in Massachusetts. We use complementary synthetic control instrumental variables (IV-SC) and differences-in-differences instrumental variables (IV-DiD) estimators. The results suggest greater charter attendance increases per-pupil expenditures in traditional public schools and induces them to shift expenditure from support services to instruction and salaries. At the same time, charter expansion has a small positive effect on non-charter students' achievement.