This is the twenty-first volume in the Clarendon Edition of the Works of John Locke. The series aims to provide authoritative critical editions of all the writings of one of the most important intellectuals in the early-modern Anglophone world. The present volume completes the Correspondence edited by the late E. S. de Beer, published between 1976 and 1989. It contains some 300 documents: newly discovered or augmented, or newly collected, letters by or to Locke, or between his close associates. New finds have emerged from archives worldwide; previously known letters are now improved from new manuscripts or supplemented by enclosures that had become detached from them; ‘epistles dedicatory’ in books by Locke or addressed to him are collected; third-party letters with direct bearing on Locke are included; as also Locke’s agreements with publishers for the printing of his books. The volume covers Locke’s manifold interests, from childrearing to medicine to cartography; from the exercise of patronage to the political economy of England’s burgeoning empire; from the management of his Somerset tenants to relations with fellow philosopher Damaris Masham; from a trial for heresy to surveillance letters when Locke was suspect; from book collecting to calendrical reform. Locke’s critics and vindicators are here, attacking and defending his published works. Considerable material has come to light bearing on Locke’s encounters with Carolina and policies when a founding member of the Board of Trade and Plantations. The volume is supported by Mark Goldie’s introduction and by an extensive explanatory editorial apparatus.