Within the central topics of the debate on teachers' professionalism are the problems of research-based and evidence-based initial and lifelong teacher behavior. Although the statements on professional similarities of teacher actions with those of other (academic) professionals are very plausible, there remains a central task for teacher education programs: How to develop towards such expertise-which is equal to evidence convictions-effectively and efficiently. Which role do scientific research and its results play in this context? How can research results be converted into recommendations for teacher actions?