The rapid expansion of charter schools has fueled concerns about their impact on traditional public schools. I estimate the effect of charter openings on traditional public schools in Massachusetts and North Carolina by comparing schools near actual charter sites to those near proposed sites that were never occupied. I find charter openings reduced public school enrollment by around 5 percent and reduced White enrollment in North Carolina. I find no impact on student achievement, and my 95 percent confidence intervals rule out effects larger than ±0.05 standard deviations. I find no effects on attendance or suspensions. [This paper was published in "American Economic Journal: Economic Policy" v14 n2 p445-474 2022.]