The more radical trends in Pietism are no longer seen by researchers as a marginal part of an otherwise well-integrated religious movement, but rather as a genuine component of one of the most important reform movements in European and North American Protestantism.This volume contains the newest research contributions concerning well-known and less well-known figures from radical Pietism, such as the Petersen couple, Gottfried Arnold and Gerhard Tersteegen. In addition, it addresses radicalism as one of the overall defining factors of Pietism – for example, with Francke, Zinzendorf and the Moravian Church as well as among representatives of Lutheran orthodoxy. With this the authors present the state-of-the-art research and develop new pespectives for future research on this phenomenon.