The rise of naturalistic, informal gardening in eighteenth-century Britain was an extraordinary development in the history of art. The British of the time touted the originality of the style, and they acknowledged few influences. We consider here the role played by one model for the new manner, namely, landscapes present in Italian Renaissance painting. Modern literature has neglected this source, and emphasized instead, for example, the influence of Asian gardens or seventeenth-century landscape painters such as Claude Lorrain. The present article suggests that awareness of Italian Renaissance pictures helped paved the way for those British gardeners, critics, theorists, and landowners who adopted or accepted the new natural style. Indeed, the great age of eighteenth-century landscape gardening coincided with the era of the first flourishing of the Grand Tour and of expanded collecting by the British of Renaissance art. We give special emphasis here to William Kent, whose travels within Italy are well-documented, and who was especially important in the development of landscape gardening of his century.