The study of Pedagogical Content Knowledge (PCK) that is presented in this paper aims to obtain an impression of teachers' knowledge and beliefs concerning teaching evolutionary theory. The starting point of this project was the development of the Educational Reconstruction for Teacher Education model (ERTE). The PCK-study shows that teachers' attitudes toward students' conceptions of evolutionary theory are not always constructive and that teachers often lack awareness of the historical nature of biology. Scenario questions proved to be effective interview items in order to acquire a detailed picture of teachers' ways to react to students' pre-scientific conceptions. (Contains 1 figure.)