In Stage 5 of the German National Educational Panel Study (NEPS), we are focusing on upper secondary education in academic school tracks and the subsequent transitions. We give an overview of prior empirical studies of the upper secondary level and describe a number of unresolved general research questions that are being focused on in Stage 5. These questions mainly address the comparison of traditional and nontraditional pathways to the Abitur (the general qualification for university entrance), the academic achievement levels of Abitur students (in different school types), social disparities (in traditional and nontraditional Gymnasium), and how well achievement indicators (school grades, competencies, Abitur certificate) predict students’ further development. Although the NEPS research instrument is very broad, these guiding questions are central for its development. In addition to the panel study, Stage 5 is implementing two supplementary studies to reflect changes due to reforms of the Gymnasium and their consequences for the interpretation of NEPS longitudinal data. One study focuses on the organizational reform in Thuringia; the other on the reduction in the number of years of schooling for the Abitur (G8 reform) in Baden-Wuerttemberg. Both studies are described in some detail. The chapter closes with a short summary of the valuable contributions of NEPS in Stage 5.