Richard Baxter (1615-1691) was among the most prominent English nonconformist divines. Baxter found common ground with the Puritans but sought unity among Protestants in general. A highly independent thinker, he had opinions - and often expressed them - about every major controversy in England during his lifetime. He wrote over 140 published works, among them long, controversial discourses on doctrine but also polemical works against Quakers, Baptists and Roman Catholics, among others. Baxter found himself a peacemaker during the English Civil Wars: a chaplain for the parliamentary army, he also supported the restoration of the king. As a moderate, Baxter was a target for both extremes. He eventually registered himself as 'a meer Nonconformist', breaking with the Church of England because of his opposition to its form of episcopacy. He suffered bouts of imprisonment for his religious views and conduct during the reigns of Charles II and James II. Dr Williams's Library, London contains most of Baxter's extant manuscripts, including several 'volumes' of his unpublished 'Treatises', numbering roughly 369 items in total. The volumes, ranging from the 1630s to 1690s, consist of tracts, disputations, sermons, exercises, letters, miscellaneous papers and drafts, some of which were later incorporated into Baxter's published autobiographical writings, Reliquiae Baxterianae (1696). The treatises themselves, however, have been largely overlooked. Here, they are catalogued with clear summaries of their content, and they afford rich opportunities for research. This catalogue, the first detailed listing and description for 150 years, provides a physical description and a scholarly outline of each treatise. A comprehensive introduction sets these papers in context. ALAN ARGENT is Research Fellow at Dr Williams's Library, London and minister of Trinity Congregational Church, Brixton. He has written a biography of Elsie Chamberlain, a history of Congregationalism in the twentieth century and has edited The Angels' Voice for the London Record Society. His 2016 Friends of Dr Williams's Library lecture Dr Williams's Library 1729-1793 - 'a good library, under the direction of the dissenters' was published in 2017. He is preparing a history of Dr Williams's Library and Trust 1716-2016.