Proposing a rhetorical definition of fictionality as intentionally signaled invention in communication, this article shows how a historical investigation of fictionality can inform our understanding of the rise of the English novel in the eighteenth century. The essay situates its approach to fictionality in relation to work on the concept by both historians of the novel, especially Catherine Gallagher, and narratologists, especially Richard Walsh. The essay then analyzes salient passages related to fictionality in Fielding’s Tom Jones (1749), Horace Walpole’s The Castle of Otranto (first edition 1764, second edition 1766) and Austen’s Northanger Abbey (1888, written in 1798–99). These analyses demonstrate that signs and discussions of fictionality in the early novel change in ways that reflect the development of the genre: whereas Fielding and Walpole explicitly proclaim to be founders of new provinces of writing, Austen incorporates a discussion of fictionality into the established but still-contested genre. More generally, the essay shows that the discourse on fictionality within the early novel reveals how its practitioners understood the genre’s relations to realism, to truth, and to the neighboring genres of romance and history.