This book is about family and corruption. Naturally, family occupies a far deeper and more enduring place in social life than corruption ever could. Nearly everyone has firsthand experience of family; it is the primary social unit, the fundamental fabric, the building block of society. Corruption, by contrast, is typically seen as a deviation—a distortion of the norms and values that family life helps to uphold. Yet reality challenges this presumed opposition between family and corruption, as they often go hand in hand. Situations involving family members and opportunities for corruption are more common than we typically realize. It may be surprising that most companies worldwide are family-run, blending the informal norms of the family with impersonal business rationality (European Commission, 2008; La Porta et al., 1999; Song et al., 2021). Top-level politicians appoint family members widely to government positions or have their close relatives elected to high office, even in most so-called democratic Western countries (Loxton, 2024). But family members can also get involved in corruption in many other ways. Public officials can award government contracts to companies owned by relatives. Managers in private companies can use their position to secure jobs or benefits for family members, regardless of qualifications. Family members can act as intermediaries in illicit dealings by introducing corrupt partners to one another. A mayor might direct municipal workers to renovate a relative’s home using city equipment and materials. The examples are numerous. But why does this happen? What roles do relatives play in successfully facilitating a corrupt transaction? Can corruption, paradoxically, help keep families together by strengthening social cohesion? I attempt to answer these questions in this book. I focus on a specific social configuration in which family and corruption interplay: situations where family membership is an essential element of a corrupt transaction. I call this phenomenon “family corruption.”