Large-scale studies assess mathematical competence in large samples. They often compare mathematical competence between groups of individuals within or between countries. Although large-scale research is part of empirical educational research more generally, it is also linked to more genuine mathematics education research traditions, because sophisticated methods allow for empirical verifications of theoretical models of mathematical competence, and because results from large-scale assessments have influenced mathematics education practices. This chapter provides an overview of large-scale research in mathematics education in German speaking countries over the last decades. After a brief review of historical developments of large-scale assessments in Germany, we focus on the development of competence models in Germany and Austria. At the end of this chapter, we reflect on recent developments and discuss issues of large-scale assessments more generally, including an international perspective.