Field theory is considered a precursor to today's systems theory, but it offers a somewhat different perspective on systems. With the rediscovery of its founder Kurt Lewin, it gains new relevance. Change in perception is essential for behavior to change. Adhering to this field-theoretical maxim, Monika Stützle-Hebel and Klaus Antons direct attention to the relevant connections and processes in social systems. Using field theory, they explain principles of dynamics as well as the interactions and counteractions of field forces within individuals, groups, teams, and organizations. The simplicity of Lewin's change model serves as a guideline for developmental approaches while simultaneously challenging one's own creativity. With this introduction, the authors fulfill the often-cited statement by Kurt Lewin that there is nothing more practical than a good theory.