Throughout human history, civilizations have stratified their citizens, often by establishing royal, priestly, executive, or warrior castes. Many who have achieved elite-level power joined their civilizations' premier organizations not through birthright or sociopolitical attainment, but rather by completing codified rites of passage that demonstrated their exceptional physical, spiritual, or psychological capabilities, and their deep commitment to their cultures. Crucibles: History's Most Formidable Rites of Passage explores fourteen elite organizations, with a special emphasis on the onerous trials designed to cull initiates from aspirants. It analyzes the underlying commonalities of such trials, describing how they work, why people are willing to subject themselves to such rigors, and how such tests benefit or harm the organizations that require them. Crucibles distills both positive and negative perspectives on tests and trials into actionable concepts which may be deployed in modern business, social, academic, or political spheres. In a time where there is a long-overdue focus on the ethical roles and responsibilities of cultural gatekeepers, Crucibles stands as a valuable resource for leaders and managers seeking to convert historic practices into useful, moral, and legal modern policies.