Prior research has shown that quantity of schooling affects the development of intelligence in childhood and adolescence. However, it is still debated whether other aspects of schooling--such as ability tracking or, more generally, school quality--can also influence intelligence. In this study, the authors analyzed intelligence gains in academic- and vocational-track schools in Germany, testing for differential effects of school quality (academic vs. vocational track) on psychometric intelligence. Longitudinal data were obtained from a sample of N = 1,038 Grade 7 and 10 students in 49 schools. A nonverbal reasoning test was used as an indicator of general psychometric intelligence, and relevant psychological and social background variables were included in the analyses. Propensity score matching was used to control for selection bias. Results showed a positive effect of attending the academic track. (Contains 7 table, 2 figures and 3 footnotes.)