The volume is in two parts. Part One is a new edition of "Grace and Freedom: Operative Grace in the Thought of St Thomas Aquinas", four articles written by Lonergan in 1941-42, first published in book form in 1971. This edition includes new notes and indices. Part Two is Lonergan's doctoral dissertation, "Gratia Operans", submitted to the Gregorian University, Rome, in 1940. Published here in full for the first time, the dissertation provides important context and background for the articles in the first part. Lonergan's thesis is that, from the sixteenth century onwards, commentators on Thomas Aquinas lacked historical consciousness, raised questions that Thomas had never considered, and obfuscated the issues. Lonergan's achievement consists in having retrieved the actual position of Thomas by adopting a historical approach that has reconstructed his intellectual development on grace. The majority of contemporary theologians now agree with the implementation of the historical method. What Lonergan also adds is a unique diagnosis of the mistakes made by the modern scholastic authors in their treatment of grace. Throughout this work, Lonergan discovers in Thomas a mind in constant development, displaying radical shifts on fundamental questions. Together the two parts not only reveal an essential step in Lonergan's own development, but also make an impressive contribution to Thomist studies.