In 2008, the Chilean government remade its 27-year-old universal school voucher program to introduce more regulation and accountability. The changes also gave greater emphasis to children from low-income families. A team of researchers--Richard J. Murnane, Marcus R. Waldman, John B. Willett, Maria Soledad Bos, and Emiliana Vegas--studied how these changes influenced the socio-economic makeup and student test scores in public and private schools.
They found that, on average, student test scores increased markedly, and income-based gaps in those scores declined by one-third in the five years after the passage of new law. The combination of increased support of schools and accountability, they found, was the critical mechanism through which the reforms increased student scores, especially in schools serving high concentrations of low-income students. Migration of low-income students from public schools to private voucher schools played a small role.