In this study, we investigate whether nonpublic school enrollment affects the performance of public school districts. If homeschooling and private schools act as competition, public school districts test scores should be positively associated with nonpublic enrollment. Using data on West Virginia county school districts, and controlling for endogeneity with an instrumental variables approach, we find that a one standard deviation increase in relative nonpublic enrollment in a county is associated with statistically significant increases in public school district test scores. Our findings thus confirm that nonpublic enrollment and the competition it provides act to improve, rather than impede, public school performance.