Act II begins a week later. Penny is conversing with a drunken actress, Gay Wellington, who soon passes out on the couch. Tony Kirby and his parents are scheduled to come for dinner the following night, and Alice is busy preparing, checking a list of tasks that need to be done. Meanwhile, the rest of the family indulges in their various hobbies. Penny decides to finish a painting of Mr. De Pinna as a discus thrower, which she started years ago. Mr. De Pinna dons a Roman costume and poses for her. Kolenkhov arrives to give Essie a dance lesson, and she energetically pirouettes and leaps around the room while Grandpa throws darts.

At this moment, the Kirbys, dressed in formal evening attire, unexpectedly arrive. Tony has mistakenly brought them a night early. The Kirbys are shocked by the chaotic scene, and the Sycamores are equally surprised by their unanticipated guests. Nevertheless, everyone attempts to make the best of the situation. Penny hurriedly gives instructions about dinner to Rheba, who sends Donald running to the market. As everyone tries to engage in conversation, things go comically wrong. The drunken actress awakens from the sofa, Kolenkhov grabs Mr. Kirby in an attempt to wrestle, and Penny initiates a word association game that embarrasses the guests. Just as the Kirbys decide they can't stay for dinner and are about to leave, three F.B.I. agents arrive and block the door. They are there to arrest Ed for the seemingly subversive circulars he has been printing. The agents search the house, and when they discover the "munitions" (Paul's fireworks) in the basement, they arrest everyone in the house, including the bewildered Kirbys. To top it all off, Mr. De Pinna has left his lit pipe downstairs with the fireworks, leading to a massive explosion at the end of the act.