Act III opens the next day as Rheba is setting the dinner table and Donald is reading to her a newspaper report of last night's arrests stating that all thirteen people were given suspended sentences for manufacturing fireworks without a permit.
Alice has broken off her engagement and is packed and ready to leave town. No one has called her a cab as she requested, and while she waits for one, Tony arrives to try and talk her out of leaving. At this point, Kolenkhov shows up with his friend, a former Grand Duchess named Olga who is now a waitress. He has brought Olga to make blintzes for the family and takes her into the kitchen to cook. Then, Mr. Kirby appears at the door looking for Tony. Alice is still trying to leave, but Grandpa stops her from going and gets everyone to stay and talk.
In the course of the ensuing conversation, everything gets resolved. It comes out that Tony purposely brought his parents to dinner on the wrong night because he wanted them to see Alice's family as they really were. Tony has decided to leave his job at Kirby & Co. and instead do something he really likes. Grandpa helps persuade Mr. Kirby that he should let his son pursue his dreams, since there is more to life than accumulating money. After all, "you can't take with you" when you die. To cap off the happy moment, a letter arrives from the I.R.S. saying that Grandpa's tax problems are resolved. The play concludes with everyone happily sitting down to a bountiful meal of Olga's blintzes.