In this study, we investigate whether non-public school enrolment 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 non-public enrolment. 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 non-public enrolment in a county is associated with statistically significant improvements in public school district test scores. Our findings thus confirm that non-public enrolment and the competition it provides act to improve, rather than impede, public school performance.