Essay contained in Windows on that World: Essays on British Art presented to Brian Allen (pp. 51-80). The context and function of Wilson's drawings are outlined but the main purpose of the essay is to survey some of the major private collections of the drawings made over the two centuries or so betweeen Wilson's departure for Italy in 1750 and the publication of Brinsley Ford's seminal book [Ford 1951]. It also explores how such private collections have created and nourished public ones in Britain and the USA.