This booklet discusses the pros and cons of using public funds for vouchers or other plans to subsidize the costs of private schooling. An important but sometimes overlooked issue in the school-choice debate is how private schools might change if they accepted government support. Some lessons can be found in the experiences of other industrialized nations. Many nations in Europe and elsewhere have long provided government aid to private elementary and secondary schools, including religious schools. These countries have already faced such questions as whether to regulate private schools and how to hold them accountable for public funds. To see what the United States might learn from them and to stimulate further discussion, the Center on Education Policy reviewed information from research studies, government documents and other sources about private school funding and regulation in 22 nations. It found that when private schools accept significant levels of public funding, they usually must comply with a rather high degree of government regulation. (DFR)