Previous studies from German-speaking areas of Europe could not prove any substantial development in the competences and the pedagogical content knowledge of prospective history teachers during teacher training, and thus could not empirically confirm the effectiveness of teacher education. We report on the theoretical framework and the results of a new study on the development of knowledge of lesson planning. In the present study, the development of this kind of knowledge could be confirmed by different test instruments. We found significant differences in the level of knowledge between various cohorts of prospective history teachers (n = 282), but some deficits in history teacher training can also be identified.