Since the last edition of this definitive textbook was published in 2013, much has happened in the field of animal behavior. In this fourth edition, Lee Alan Dugatkin draws on cutting-edge, new work not only to update and expand on the studies presented, but also to reinforce the previous editions' focus on ultimate and proximate causation, as well as the book's unique emphasis on natural selection, learning, and cultural transmission. The result is a state-of-the art textbook on animal behavior that explains underlying concepts in a way that is both scientifically rigorous and accessible to students. Each chapter in the book provides a sound theoretical and conceptual basis upon which the empirical studies rest. A completely new feature in this edition are the Cognitive Connection boxes in Chapters 2-17, designed to dig deep into the importance of the cognitive underpinnings to many types of behaviors. Each box focuses on a specific issue related to cognition and the particular topic covered in that chapter. As Principles of Animal Behavior makes clear, the tapestry of animal behavior is created from weaving all of these components into a beautiful whole. With Dugatkin's exquisitely illustrated, comprehensive, and up-to-date fourth edition, we are able to admire that beauty anew.