 John Locke (1632–1704) added the chapter in which he treats persons and their persistence conditions (Book 2, Chapter 27) to the second edition of An Essay Concerning Human Understanding in 1694, only after being encouraged to do so by William Molyneux  (1692–1693).[1]  Nevertheless, Locke’s treatment of personal identity is one of the most discussed and debated aspects of his corpus. Locke’s discussion of persons received much attention from his contemporaries, ignited a heated debate over personal identity, and continues to influence and inform the debate over persons and their persistence conditions. This entry aims to first get clear on the basics of Locke’s position, when it comes to persons and personal identity, before turning to areas of the text that continue to be debated by historians of philosophy working to make sense of Locke’s picture of persons today. It then canvases how Locke’s discussion of persons was received by his contemporaries, and concludes by briefly addressing how those working in metaphysics in the twentieth and twenty-first centuries have responded to Locke’s view—giving the reader a glimpse of Locke’s lasting impact and influence on the debate over personal identity.