Focusing on Germany, this article presents results from the international comparison of fifteen-year-olds in collaborative problem solving and a cross validation of the scaling in the Programme for International Student Assessment (PISA) 2015. A new computer-based test was used requesting students to solve a problem jointly with simulated group members. Data from collaborative problem solving of fifteen-year-olds (n = 124,994) in 51 countries were assessed. The German mean competence level (525 points) is a quarter standard deviation above the OECD average (500 points) and a quarter standard deviation below the OECD’s top performing country Japan (552 points). In all participating countries, girls outperform boys. While the percentage of top-performing students in Germany is comparable to proportions in the best-performing OECD countries, 21% of the students in Germany only reach competence level I or below, twice as many as in Japan. National results are presented as well as empirical evidence on the quality of the test, which is critically discussed.