Teachers’ pedagogical knowledge is expected to affect the process quality of teaching and—thereby—the learning outcome of students implicitly. However, empirical evidence for this expectation is limited so far. Furthermore, it is sometimes questioned whether this knowledge is explicit, which means that it can be communicated by teachers and is consciously applied in classroom situations. In the present paper, a new test instruments is introduced, which can be used – in an applied way with focus on concrete classroom situations—for assessing declarative and conditional/procedural components of the pedagogical knowledge of teachers. Based on two studies with science teachers, the psychometric properties of the instrument are investigated. Results indicate that the pedagogical knowledge is reliably assessed in terms of two separate dimensions. Differences between participants of different vocational training levels as well as correlations with tests of content knowledge and pedagogical content knowledge provide evidence for its construct validity.