The phrase "sentimental fiction" usually refers to novels published in Europe during the 18th century. These works were generally marked by their use of conventional situations, stock characters, and rhetorical devices to arouse a feeling of pathos in the reader. As The Vicar of Wakefield both employs and subverts the conventions of the genre, it is useful to understand it when reading the novel.
In sentimental fiction, emotion is touted as superior to reason. The novels all accepted a popular 18th century belief that claimed human emotions as pure and good, derived from a natural state. As a result, its novels have a tendency towards being emotionally overwrought. (What most immediately distinguishes Vicar from its potential peers is its heavy use of wit and irony.)
The characters in these novels are often extremely, if not cloyingly, virtuous. Further, they are posed against a hostile world for which they are initially unfit. However, their emotions and superior judgment leads them to continue along the path of righteous conduct until they eventually triumph over their adversaries. In this way, sentimental fiction tends to be extremely moral and didactic, even when the author does not underline those lessons.
The first sentimental novel is also one sometimes considered the first novel written in English: Samuel Richardson's Pamela (1740). Richardson's next novel, Clarissa (1747-48), is also a paragon of the genre. He appealed to a mostly female readership by utilizing a common plot trope of the day – that of a young poor woman working her way up through society. His novels, like many of those in the genre, were told in a histrionic first-person style, and included the text of the narrative as well as letters written by the characters. The more serious writer Henry Fielding parodied Pamela with his own Shamela (1741).
Some of the most famous sentimental novels include English writer Laurence Sterne's A Sentimental Journey (1768), French writer Jean-Jacques Rousseau's La Nouvelle Heloise (1761), and the German writer Goethe's The Sorrows of Young Werther. Frances Burney's Evelina (1778) is also considered to be a sentimental novel, though it expanded on the style in notable ways.
Sentimental fiction fell out of favor in the 1800s. Writers like Jane Austen and Elizabeth Gaskell deplored the predictability of its plots; the former's Sense and Sensibility (1811) is commonly assumed to satirize the genre's excesses. The reading public also began associating sentimental novel with "sex tales," as many of them featured young women being seduced by rapacious men. Young girls were encouraged to avoid such tawdry tales, ironic considering that the novels initially aimed to tout the very virtues they were now accused of corrupting.
Ultimately, The Vicar of Wakefield utilizes the sentimental conventions in a way that makes it a breezy, charming story, while also upending those conventions to make much more serious observations about human nature.