Selfishness is everywhere-woven into our choices, our relationships, our politics, and even our biology. Whether we admire it, condemn it, or quietly recognize it in ourselves, selfishness shapes daily life in ways we rarely stop to examine. But what does psychology have to say about this trait?This wide-ranging book explores sixteen fundamental questions about selfishness, drawing on insights from psychology, evolutionary biology, the social sciences, the humanities, and the lived experiences of everyday people. What exactly is selfishness? Is it a stable personality trait? Is it morally wrong-or sometimes beneficial? Does it help us meet our needs, win social games, or find fulfillment? Are we selfish by nature, or shaped by culture and development? And how should we respond to selfishness in ourselves and others?Balancing scientific rigor with accessible analysis, Selfishness: A Multidisciplinary Approach examines why some people are more selfish than others, how selfishness changes across the lifespan, and whether humanity is becoming more or less selfish over time. The result is a nuanced, thought-provoking guide to understanding one of the most consequential forces in human behavior-and a roadmap for navigating it with clarity and insight.