For much of the 20th century, British students were tracked into higher-track (for the "top" 20%) or lower-track (for the rest) secondary schools. Opponents of tracking contend that the lower-track schools in these systems will inevitably provide low-quality education. In this paper I examine this claim using a 1947 reform that increased the minimum school leaving age from 14 to 15. First, I show that over 95% of the students affected by the reform ("compliers") attended lower-track schools. Second, using new data, I show that for both men and women, the additional schooling induced by the reform had close to zero impact on a range of labor market outcomes including earnings. Third, I show that lower-track schools featured, among other things, large classes and a curriculum that promoted practical education. I conclude that my findings shed new light on the potential consequences of educational tracking.