Would large-scale, free-market reforms improve educational outcomes for American children? This question cannot be reliably answered by looking exclusively at domestic evidence, much less by looking exclusively at existing "school choice" programs. Though many such programs have been implemented around the United States, none has created a truly free and competitive education marketplace, being too small, too restriction laden, or both. To understand how genuine market forces affect school performance, we must cast a wider net, surveying education systems from all over the globe. The present paper undertakes such a review, assessing the results of decades of international research comparing market and government provision of education and explaining why these international experiences are relevant to the United States. In more than 150 statistical comparisons covering eight different educational outcomes, the private sector outperforms the public sector in the overwhelming majority of cases. Moreover, this margin of superiority is greatest when the freest and most market-like private schools are compared to the least open and least competitive government systems (i.e., those resembling typical U.S. public school systems). Given the breadth, consistency, relevance, and decisiveness of this body of evidence, the implications for U.S. education policy are significant. (Contains 3 tables, 2 figures and 9 notes.)