Given the increasing diversity of the student body, teachers are called to appropriately address students' various learning needs by means of differentiated instruction (DI). However, empirical research has yielded mixed evidence on teachers' reported use of DI. Using nationally representative data from the National Educational Panel Study in Germany, this article aimed to explore German (as native language) and Mathematics teachers' use of DI practices. In addition, this study took into consideration contextual factors, such as school track, and investigated the impact of teachers' constructivist beliefs on their DI implementation. Results from a mixed analysis of covariance indicated that teachers occasionally implement DI practices. Furthermore, between-subject effects reported differences across school tracks. It appears that advanced secondary school teachers implement less often DI practices. The covariate of teachers' constructivist beliefs was also positively linked to overall teachers' implementation of DI. Implications of the results, as well as further lines of research are discussed.