James Beggan provides a fascinating integration of two fields of study that have never before been brought together. By using game theory as the conceptual rationale for analyzing polyamory and other forms of open relationships, the author provides an important and novel framework for understanding what is rapidly becoming a legitimate and popular form of romantic and sexual expression. His focus on coalition formation in triads clarifies the challenges inherent in relationships that involve more than two people. His extensive and up-to-date literature review and historical analysis of consensual nonmonogamy will serve as a valuable reference for students, researchers, and therapists operating in a variety of disciplines.