We apply propensity score matching to the estimation of differential school effectiveness between the publicly funded private sector and the public sector in a sample of 26 countries. This technique allows us to distinguish between school choice and school effectiveness processes and thus to account for selectivity issues involved in the comparison of the 2 sectors. Concerning school choice, we found 2 patterns: a choice of upwardly mobile parents for private schools and a preference for segregation by (lower) middle-class parents. As regards school effectiveness, our results indicate that, after controlling for selectivity, a substantial advantage in reading achievement remains among students in publicly funded private schools in 10 out of the 26 countries. (Contains 1 figure, 4 tables and 15 notes.)