The Province of Quebec subsidizes nearly 50% of private education, and at the same time heavily regulates private schools. To date, no studies have been done to determine the effect of the unique nature of competition from K-12 private schools on public school education of the sort found in Quebec. The authors used multiple regression to determine the effects of private school competition on school district performance and efficiency. The authors found that private school competition has a positive, though nonsignificant, effect on school district performance. However, private school competition does have a significant, positive effect on the efficiency of public school districts. This gain in efficiency is explained by competition's influence on lowering expenditures across the board. (Contains 5 tables.)