Long thought to be the most important medieval philosopher and theologian after Scotus and the founder of late medieval Nominalism, the meaning and influence of William of Ockham’s thought have become matters of intense debate in recent years. After a survey of the changing assessment of Nominalism in the nineteenth and twentieth centuries, and a new understanding of twelfth-century Nominalism with related elements in the thought of Augustine and Anselm, this book examines the reception of Ockham’s thought at Oxford and Paris, the crisis over Ockhamism at Paris in the 1335 to 1345 period, and concludes with an examination of the legacy of Ockhamist thought in the late medieval period.