Charity is a drama in four acts by W. S. Gilbert that explores the issue of a woman who had lived with a man as his wife without ever having married. The play analyses and critiques the double standard in the Victorian era concerning the treatment of men and women who had sex outside of marriage, anticipating the "problem plays" of Shaw and Ibsen. It opened on 3 January 1874 at the Haymarket Theatre in London, where Gilbert had previously presented his 'fairy comedies' The Palace of Truth, Pygmalion and Galatea, and The Wicked World. Charity ran for about 61 performances, closing on 14 March 1874, and received tours and revivals thereafter.

Gilbert created several plays for the Haymarket Theatre, managed by John Baldwin Buckstone and starring William Hunter Kendal and his wife, Madge Robertson Kendal, sister of the playwright Thomas William Robertson, in the early 1870s. In Charity, Gilbert wanted to use what he perceived as Mrs. Kendal's capabilities as a tragedienne, and, after abandoning his original plan of a vindictive villainess, he composed one of his most powerful women's roles for her in this play.

1874 was a particularly busy year for Gilbert. He illustrated The Piccadilly Annual; supervised a revival of Pygmalion and Galatea; and wrote Charity; Rosencrantz and Guildenstern, a parody of Hamlet; a dramatisation of Ought We to Visit Her? (a novel by Annie Edwardes), an adaptation from the French, Committed for Trial, another adaptation from the French called The Blue-Legged Lady, a play, Sweethearts, and Topsyturveydom, a comic opera. He also wrote a Bab-illustrated story called "The Story of a Twelfth Cake" for the Graphic Christmas number.

Fred Smailey and Eve Van Brugh are making plans for a school feast. Fred is a very grave person, objecting to the frivolous entertainments being planned by Eve, but they are in love, and, despite her teasing and ignoring his chides, they get along quite well. Fred doesn't think Eve's mother cares much for him, although she agreed to their engagement.

Edward "Ted" Athelney, Eve's "amateur brother" arrives, and Fred claims that Eve isn't at home, to her confusion. Fred sees Ted as a potential rival – an amateur brother can so easily slip into something more – and manages to convince Eve to be less affectionate towards Ted. On learning of her impending marriage, Ted realises that he was in love with Eve, but he tries to hide it. After Fred and Eve leave, he admits it to Eve's mother, but he cares too much about Eve to let her know, now that she's engaged to be married.

Dr. Athelney appears to thank Mrs. Van Brugh for a favour, and she asks his advice about what to settle on Eve, as Fred's father intends to do nothing, claiming that all his money is tied up. In the course of conversation, Mrs. Van Brugh's husband's first wife is mentioned, but the discussion is interrupted by servants dragging in Ruth Tredgett, a tramp who was caught trying to steal from them. She arrogantly admits to the theft, and Dr. Athelney condemns her. Mrs. Van Brugh, however, plans to reform her, having learned Ruth's history: born into poverty, raised among thieves, falling victim to a "psalm-singing villain" who had his way with her then abandoned her. Athelney's moralistic arguments fail in the face of this history, and he admits that her life was "what God knows it couldn't well have helped being under the circumstances." Mrs. Van Brugh promises to do everything in her power to help Ruth out of criminality, and Ruth, stunned, agrees to it.

Smailey arrives at Van Brugh's house with Fitz-Partington, a private detective disguised as Smailey's solicitor, to discuss Fred and Eve's marriage settlement. Mrs. Van Brugh proposes to settle on them a farm in Buckinghamshire left to her by her godfather, but she isn't aware if it is a leasehold or a freehold. Smailey offers to fetch the will, which Mrs. Van Brugh hasn't actually seen, to clarify the point. Smailey also brings up the subject of Ruth, who has been established as a needlewoman nearby. He considers this a violation of all that is decent, which shocks Mrs. Van Brugh, who forcefully argues in Ruth's defence. Ruth arrives, and Mrs. Van Brugh leaves. Smailey begins to lecture Ruth on morality and the impertinence of her "imposture". Ruth interrupts him, having recognised him as the "psalm-singing villain" who had caused her fall. Smailey tries to backtrack and begins to expose all the tangled ways that he has justified his own behaviour while condemning others. Ruth, a bit exasperated, still forgives him, as she hopes to be forgiven. Smailey is shocked that someone like her would dare to adopt such a tone with him, and begins to attack Mrs. Van Brugh again. Ruth furiously stops him, saying that Mrs. Van Brugh is "a bit chipped off heaven. ... She's—She's—I'm slow at findin' words that mean goodness. My words run mostly the other way, wus luck."

Smailey says he has no desire to be hard on her, but that "it is a fraud". Ruth points out he was guilty of fraud, and she has evidence to prove it. Smailey tries to buy it from her, but she's respectable now: She won't take his money, though she keeps the papers as she "ain't a fool"; Smailey leaves. Fitz-Partington interviews Ruth, to her confusion. Mrs. Van Brugh re-enters, and Fitz-Partington warns her about Smailey, explaining that his detective agency was called on to find out about Smailey's fraud, but as Smailey then hired him to investigate Mrs. Van Brugh, they had combined the cases. However, Fitz-Partington goes on to ask several further questions about Mrs. Van Brugh's marriage, and she begins to realise what Smailey is looking for: if Mrs. Van Brugh's godfather had called her Captain Van Brugh's wife in his will, her secret might be revealed. Smailey returns with the will, and reads out the relevant section about the farm, ending with the section referring to her as "Catherine Ellen, wife of Captain Richard Van Brugh." She faints into a chair.