In recent research, Aristotle's substance books in metaphysics are among the most discussed texts. Over the past two and a half decades, an extensive discussion has developed, leading to a completely new understanding of Aristotle's theory of substance. However, a comprehensive overview of this discussion and the latest state of research has not been available in the German-speaking world until now. This volume addresses that gap. Its contributions present different viewpoints and reflect the current state of research, providing a foundation directly derived from research for both seminar discussions and personal engagement with the topic. Contributions by: Andreas Anagnostopoulos, Thomas Buchheim, Mary Louise Gill, Donald Morrison, Christof Rapp, Holmer Steinfath, Walter Mesch, and Michael V. Wodin.