For many years, (descriptive) statistics had an inferior standing in schools worldwide. However, in recent years, a considerable shift from probability to statistics is apparent with regard to National Standards for Mathematics. Nevertheless, studies about teachers’ professional knowledge in this new domain are scarce, particularly in Germany, although it is verifiable that the teachers’ knowledge has an impact on their classroom practice and also on students’ learning. Therefore, a main focus of the research presented here is to generate a questionnaire to survey teachers’ professional knowledge in the domain of descriptive statistics. The theoretical basis is on the one hand Ball’s model of professional knowledge and the concept of ‘statistical literacy’ on the other hand. Thus, the theoretical background and its realization in the test instrument itself are presented and discussed.