In this essay, I begin by distinguishing Pynchon's fictional character of William Slothrop from his real-life counterpart: Thomas Pynchon's colonial ancestor William Pynchon. By pointing out the similarities and also the differences between the historical Pynchon and the literary creation of his eleventh-generation descendant I am able to highlight recurring themes and images in the text of Gravity's Rainbow and to suggest how these inherited points of interest have been developed in subsequent works, such as Mason & Dixon. I begin, then, with a brief chronological account of the life of William Pynchon. Aspects of his life, such as his heretical ideas expressed in The Meritorious Price of Our Redemption (1650) and his involvement with controversial debates such as the Remonstrants' Petition, signal his status as model for the dissenting Puritan William Slothrop. However, this is a very partial representation of William Pynchon whose activities as a statesman, entrepreneur, frontiersman, and politician illuminate elements of Gravity's Rainbow not usually associated with the character of William Slothrop. These elements include: the family as empire; the critique of capitalism; the politics of colonialism; the construction of nation states and the determination of political boundaries; the psychology of power and the suppression of dissent. Gravity's Rainbow is one place where Thomas Pynchon explores many of the implications of his ancestor's colonial adventure: in his representation of relationships between colonizers and their colonized; in his investigations into the psychology of capitalism and its relationship with Protestant/Puritan theology; in his depiction of “Them” and the political manipulations of sovereign nation-states “They” achieve to further their own ambitions; and in his literary portrait of the Slothrop family which bears so many key similarities to the historical Pynchon family. My aim is to offer an historical analogue to the classic interpretations of Gravity's Rainbow and indeed the entire Pynchon canon. This paper seeks to extend the power of these interpretations by showing how Thomas Pynchon – that most private of contemporary writers – reveals his own engagement with the details of his family past.