Increasing the share of vocational secondary schooling has been a mainstay of development policy for decades, especially in formerly socialist countries. However, the transition to market economies led to significant restructuring of school systems and a decline in the number of vocational students. Exposing more students to a general curriculum could improve academic abilities. To test the hypothesis that delayed vocational streaming improves academic outcomes, this paper analyses Poland's significant improvement in international achievement tests and the restructuring of the education system, which expanded general schooling. Using propensity-score matching and difference-in-differences estimates, the authors show that delaying vocational education had a positive and significant impact on student performance on the order of one standard deviation. (Contains 6 figure, 9 tables and 2 footnotes.)