Early English readers of Michel de Montaigne (1533–92) annotated their copies of John Florio's (1553[?]–1625) translation with remarkable frequency and vehemence, creating a context within which printed appropriations of the essayist may be fruitfully examined. No topic intrigued these readers more than custom. Drawing from transcriptions of over 4,000 marginal annotations and situating the Montaignean borrowings of William Shakespeare (1564–1616), Sir Francis Bacon (1561–1626), and other English writers within a culture of active reader response, this essay treats the Montaignean account of custom as a case study wherein differences between manuscript and print appropriation may be investigated. Montaigne's reception in seventeenth-century England cannot be understood without scrupulous attention to both traditions.