- This act takes place in Olga and Irina's bedroom (guess Bobik got his room). Fire alarms are heard in the distance.
- Masha's lying on the sofa. She doesn't seem to care about the bells.
- The old servant Anfisa enters, talking about the Vershinin daughters, who are downstairs. They've been run out of their house by a fire. Those alarm bells ain't for nothing.
- Olga is collecting clothes. The family will host the Vershinins and other affected families.
- She can't put anyone in with Chebutykin. He had been on the wagon, but he fell off. In other words, he's drunk again.
- Anfisa suddenly begs Olga not to send her away. Olga has no intention of doing so.
- Natasha comes in and lashes out at Anfisa for sitting down. Guess that's what Anfisa was really worried about. Anyway, Olga is appalled by Natasha's rudeness.
- Masha exits.
- Olga and Natasha have a huge fight. At the end of it, Natasha suggests Olga move into the basement apartment so they can stop bickering. Anyone notice a trend here?
- Kulygin enters looking for Masha. She's not there. He hides behind a screen to surprise the doctor.
- Chebutykin enters drunk and delivers a long monologue full of self-loathing.
- Irina, Vershinin, and Tuzenbach enter. Tuzenbach is dressed as a civilian.
- Tuzenbach has been asked to organize a benefit concert for the victims of the fire. When he suggests Masha play the piano, Kulygin expresses his concern. It might not be appropriate.
- Chebutykin purposefully breaks a clock that belonged to the girls' mother. He mentions Natasha's affair with Protopopov and leaves. Whoa, dude. Chill.
- Vershinin has a long monologue describing the scene of the fire: his little girls in their underwear, their mother not around, and chaos everywhere. It's another of those philosophy-soaked speeches he loves to spout.
- Fedotik enters. He doesn't do much, though.
- Solyony tries to come in to the bedroom but Irina doesn't want him to. He's mad that the baron (Tuzenbach) is allowed in, but he's not.
- Solyony leaves with Vershinin and Fedotik.
- Tuzenbach declares his love to Irina. Yeah, again. Masha tells him to get out; he does. She wants Kulygin to leave, too.
- The sisters are angry that Andrey took out a mortgage on the house without asking them—or sharing the money. Plus, they're embarrassed by the affair Natasha flaunts with Protopopov, a colleague of Andrey's. And they're disappointed that he hasn't amounted to anything.
- That's a lot of grievances.
- Irina breaks down. Olga advises her to marry the baron.
- Masha confesses to her sisters that she loves Vershinin. Everyone kind of knew this.
- Andrey comes in looking for a key. He senses his sisters' resentment and confronts them.
- Vershinin comes for Masha and she leaves.
- Andrey at first tries to defend his wife and his decision to not pursue an intellectual career. He apologizes for mortgaging the house, and eventually gives up and starts crying.
- Kulygin enters looking for Masha again.
- The act ends with Irina once more begging to go to Moscow. This girl's really got a one-track mind. But with this kind of a life, can you really blame her?