Act I begins in Sir Robert Chiltern’s home in the octagon room. He and his wife, Lady Chiltern, are hosting a party. As guests enter, Lady Chiltern greets them while a large tapestry featuring François Boucher’s “Triumph of Love” (195)—probably either Boucher’s Triumph of Venus or Visit of Venus to Vulcan—hangs behind her. Lady Basildon and Mrs. Marchmont, two guests at the Chiltern home, discuss their plans for the evening and their distaste at the company they’ve encountered there so far. As they move to the music room, Lord Caversham, a politician and father to Viscount (Lord) Goring, enters and asks after his son, referring to him as a “good-for-nothing.” Lady Chiltern tells Lord Caversham he hasn’t yet arrived.

As they talk, Mabel Chiltern—Sir Robert’s sister—enters and defends Lord Goring, asking Lord Caversham why he doesn’t visit more often. He replies that he is tired of London society and rarely wishes to go out anymore. Mrs. Cheveley and Lady Markby then enter. When Lady Markby introduces Mrs. Cheveley, Lady Chiltern realizes she has met her before. Though Mrs. Cheveley does not remember, the two women went to school together.