Fielding's first venture into prose fiction came a year previously with the publication in pamphlet form of Shamela, a travesty of, and direct response to, the stylistic failings and moral hypocrisy that Fielding saw in Richardson's Pamela. Richardson's epistolary tale of a resolute servant girl, armed only with her "virtue", battling against her master's attempts at seduction had become an overnight literary sensation in 1741. The implicit moral message — that a girl's chastity has eventual value as a commodity —, as well as the awkwardness of the epistolary form in dealing with ongoing events, and the triviality of the detail which the form necessitates, were some of the main targets of Fielding's parody.
Richardson would continue to be a target of Fielding's first novel, but the Pamela phenomenon was just one example of what he saw as a culture of literary abuses in the mid-18th century. Colley Cibber, poet laureate and mock-hero of Pope's Dunciad, is identified in the first chapter of the novel as another offender against propriety, morality and literary value.
The impetus for the novel, as Fielding claims in the preface, is the establishment of a genre of writing "which I do not remember to have been hitherto attempted in our language", defined as the "comic epic-poem in prose": a work of prose fiction, epic in length and variety of incident and character, in the hypothetical spirit of Homer's lost (and possibly apocryphal) comic poem Margites. He dissociates his fiction from the scandal-memoir and the contemporary novel. Book III describes the work as biography.
As becomes apparent from the first few chapters of the novel in which Richardson and Cibber are parodied mercilessly, the real germ of Joseph Andrews is Fielding's objection to the moral and technical limitations of the popular literature of his day. But while Shamela started and finished as a sustained subversion of a rival work, in Joseph Andrews Fielding merely uses the perceived deprivation of popular literature as a springboard to conceive more fully his own philosophy of prose fiction.