Alasdair MacIntyre is one of the major philosophers of the late twentieth and early twenty-first century. After Virtue, first published in 1981, remains the book for which he is best known but, as this volume testifies, his phenomenal output extends over a period of seven decades. Not only is his output extensive, but its impact, unusually for philosophers, has been wide-ranging. As MacIntyre enters his tenth decade, this book pays tribute not just to his work, but to the way in which it has been influential across disciplines outside of philosophy. Beginning with an intellectual biography, the chapters which follow, written by experts in their fields, explore MacIntyre's contributions to theology, Thomism, moral philosophy, classical philosophy, political philosophy, Marxism, the Frankfurt School, communication, business ethics, sociology, education, law, and therapeutic method. Essential reading for scholars from across these disciplines, and for anyone who wishes to understand MacIntyre's contributions, this volume not only helps readers to appreciate what we may learn from MacIntyre, but also indicates how his work will continue to be influential.