This book is intended for readers interested in mediation, negotiation, and other methods of conflict resolution. The use of mediation is widespread, but research into its impact is still in its infancy. If mediation is a way of resolving conflicts of our time, then mediators have a responsibility: on a small scale, in resolving acute conflicts, and on a large scale, in shaping and establishing a new form of social dialogue. They should know what they are doing. They should know which interventions to use and when, and what effect they have. With its research results, this book helps to strengthen the relevant field of mediation through scientific findings and to derive recommendations for action for mediators from the results. This book is a translation of the original German 1st edition Mediatoren in der Hauptrolle – Mediation verstehen und aktiv steuern by Andrea Hartmann-Piraudeau, published by Springer Fachmedien Wiesbaden GmbH, part of Springer Nature in 2020. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). A subsequent human revision was done primarily in terms of content, so that the book will read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors.