"This book will, I predict, be immediately recognized as the first modern synthesis of behavioral endocrinology and behavioral ecology. Particularly attractive is its unusual organization. While beginning and ending with hormones, as have other leading texts, it differentiates itself by weaving through ascending levels of biological organization, showing readers how discovery at each level informs us about higher levels. In this way readers begin with DNA and by the end, in an almost seamless manner, find themselves contemplating the evolution of populations. Rather than a recitation of facts, the author poses and answers (when possible) a logical series of questions. Moreover, the writing is excellent."--David Crews, University of Texas, Austin "Adkins-Regan provides an excellent, well-written source of information that will be valuable not only to behavioral ecologists and endocrinologists but to a much wider audience within biology--where it will be valuable reading to anyone who thinks about why animals do what they do. She has incorporated and synthesized information at multiple levels, successfully bridging the gap from mechanisms to ultimate outcomes. I would be surprised if anyone who reads this book does not come away with both a new appreciation for the complexity of the relationships between hormones and behaviors, and some valuable new directions for their own research."--Stephan J. Schoech, University of MemphisAdkins-Regan, Elizabeth is the author of 'Hormones and Animal Social Behavior', published 2005 under ISBN 9780691092478 and ISBN 0691092478.