This book is dedicated to interdisciplinarity, which is characteristic of the approaches, formats and methods of foreign language didactic research. Qualitative and quantitative research approaches or mixed-methods designs are presented on the basis of current studies. A special focus is on the interdisciplinary aspects of the respective studies. The practical research examples present current or near-completion studies in empirical foreign language research. Thus, the contributions provide an up-to-date overview of foreign-language didactic research practice and contain many suggestions for research-methodological options and ethical questions, which must be weighed against newly designed studies in the interdisciplinary field of foreign language research.