A Modern Instance is American author William Dean Howells's 1882 novel about the collapse of the marriage between its two principal characters, Bartley Hubbard and Marcia Gaylord. It is considered the first serious treatment of divorce in the history of American literature and is a testament to moral values during the Gilded Age.

Bartley Hubbard, one of the novel's two principal characters, is a journalist. Early in the novel he marries Marcia Gaylord in their hometown of Equity, Maine, before relocating to Boston after a workplace dispute. He is consumed by his profession to the point of ignorance of his family's needs, essentially dismissing Marcia's efforts to baptize their daughter. Eventually he moves west, all but abandoning Marcia in the process.

Despite his deep flaws, Hubbard is not presented as an inherently evil person. Rather, his objectives in marriage simply do not align with those of Marcia. In fact, he later notes, the two were simply incompatible.

Marcia Gaylord is Bartley Hubbard's wife and the mother of their child, Flavia. Before marriage, she was enthralled by Bartley and idolized him. The eventual death of Bartley brings to an end the fractious nature of her marriage to him, allowing her to remarry. At the conclusion of the novel she returns to Equity, Maine.

Ben Halleck is a patrician Bostonian who takes pity on Marcia due to her unhappy marriage to Bartley. Halleck's friendship is more than just casual, however, as he is secretly attracted to her, a fact that Bartley uses to denounce Halleck, declaring that, "I can't marry again for two years. But as I understand the law, Marcia isn't bound in any way. I know that she always had a very high opinion of you, and that she thinks you are the best man in the world: why don't you fix it up with Marcia?" Halleck, however, constrained by the limits of his own morality, limits his expressions of desire for Marcia until after Bartley's death. Halleck has an unmarried sister.

Other characters in the story include shop foreman Henry Bird, logging camp owner Willett, newspaper publisher Witherby, the lawyer Atherton, the seductress Mrs. Macallister, Hannah Morrison, and Kinney.