This chapter introduces the tests of secondary mathematics teachers’ pedagogical content knowledge and content knowledge that were developed and administered in the COACTIV framework. It reports on the conceptualization of the two knowledge constructs based on Shulman’s (Harv Educ Rev 57(1):1–22, 1987) theoretical taxonomy of teacher knowledge, describes the construction of tests to assess the two constructs, and presents results from N=198 secondary mathematics teachers in different school tracks. Specifically, the chapter presents findings on the dimensionality of teachers’ domain-specific professional knowledge, the scaling of the tests, evidence for their reliability, and first results on construct validity. This chapter serves as the basis for Chap. 9, which examines the validity of pedagogical content knowledge and content knowledge to predict quality of instruction and student progress.