Specifically focusing on the relationship between the Eudemian and the Nicomachean Ethics, this collection of essays studies major themes from Aristotle's ethics. This volume builds on a recent revival of interest in Aristotle's Eudemian Ethics, which offers an invaluable complement to the Nicomachean Ethics in the study of the development of Aristotle's ethical ideas. It brings together a series of new studies by leading scholars covering the main points of inquiry raised by the relationship between the two works, exploring their continuities and divergences. At the same time, it showcases a variety of approaches to and perspectives on the main questions posed by Aristotle's ethical thought. Investigating the Relationship Between Aristotle's Eudemian and Nicomachean Ethics is offered as a contribution to long-standing debates over Aristotle's ethical thinking, as well as an inspiration for new approaches, which take both of his surviving ethical treatises seriously. The volume will be of interest to students and scholars of ancient philosophy and ethics, particularly Aristotle's two ethics.