Book excerpt: This two-volume exploration of what might be termed "interpersonal war and peace" reveals why individuals and groups coalesce or collide, and how more positive relationships can be achieved. In this two-volume set, the most comprehensive treatment of its subject to date, eminent social scientists explore the processes involved in becoming friends—or enemies. Volume 1, Interpersonal and Intrapersonal Insights, focuses on friendship and enmity between individuals, examining situations that arise in romances, at school, at work, and between races, genders, and sexual identities. The text is enriched by a discussion of individual interactions in classic books and movies, what those stories reflect, and what they teach about human nature. Volume 2, Group and Intergroup Understanding, focuses on group dynamics across time and around the globe. Topics range from group interactions before and after the American Civil War to friendship and enmity between Afghans and Americans today. The work's ultimate concern, however, is to present ways in which individuals, groups, and nations can learn to be friends.