It is after sunset and a make-shift, homemade stage stands in the outdoor setting of Sorin's provincial, Russian estate and farm. A lake serves as natural scenery behind the stage. Workers including Yakov are banging nails into the stage, behind a curtain. Medvedenko and Masha enter this back lawn of Sorin's property. Medvedenko and Masha debate about what makes people happy in relation to finances. Medvedenko believes he'd be a happier man and a more attractive suitor to Masha if he had more money. Masha is fixated on her love for Treplev and does not agree. She thinks poverty would be fine if she could have Treplev's love. Masha observes that Treplev's play will begin soon. Medvedenko agrees and introduces to the audience the information that their neighbor, Nina, will star in the play. Medvedenko compares Treplev and Nina's love, which he predicts will soon be unified by artistic expression to the unconnected relationship between himself and Masha. He does not know Masha loves Treplev. Snorting snuff, Masha openly acknowledges that she knows Medvedenko loves her but explains that she cannot love him back.
Though Chekhov does not break the play into official scenes, the next conversation, between Sorin and Treplev, is, for the most part, a two-person scene as well. Treplev is nervous and busy getting things ready for the first performance of his play. Sorin tries to describe the strange feelings she has while living in the countryside, including strange sleeping patterns. Treplev scolds Masha and Medvedenko for being at the play before he is ready. Sorin asks Masha to have her father tie up the dogs. She refuses, even though Sorin told her that their barking keeps his sister, Arkadina awake all night. Sorin complains about his old age and not being happy in the country. He comments on his state of living because he has no other choice, not because he enjoys life. Treplev admires the stage and his idea to have the play take place outdoors when the moon comes out. He quickly ruins his elation with the thought that Nina could ruin his plans if she arrives late. Sorin complains about his scraggly beard and his lack of luck with women. Treplev tells Sorin that Arkadina is jealous of his play and hates it even before she has seen it. Sorin laughs off this idea. Treplev goes on to describe what he feels are the many faults and few attributes of his mother. He describes Arkadina as jealous, vain, and miserly, but a good nurse, a talented actress, and an intelligent woman. Treplev picks a flower and pulls off its feathers saying, "She loves me, she loves me not," etc. He concludes that Arkadina does not love him.
Treplev goes on to explain to Sorin why he and Arkadina have differences. He brings up their differences in tastes for theater. She performs in standard morality plays that make the audience feel good, while Treplev prefers the new Symbolist movement, one full of abstract and experimental ideas and forms. Treplev also complains about his place in the social ladder and in his mother's social world. He longs to be accepted by her peers: the writers, actors and other artists who comprise the Russian intelligentsia and artistic elite. He wants respect based on his own work, not because he is the son of a famous actress.
Treplev asks his Uncle Sorin about the personality of his mother's lover, the famous writer, Trigorin. Sorin describes him as talented but not as talented as the most famous Russian writers of the day like Tolstoy. Sorin tells Treplev that Trigorin is in his late thirties, younger than Arkadina and ordinary, quiet, and fond of older women and beer. Nina arrives and Treplev's heart beats faster with his excitement and love for her. Nina is frightened because she has to get back home before her cruel father and stepmother return in half an hour. She tells Treplev that her parents are afraid she will want to become an actress if she spends time with the "bohemians" at Sorin's estate. She says that it is the lake that attracts her to the estate, "as if I were a seagull." Nina and Treplev kiss. Treplev tells her he loves her, but Nina does not return his affectionate talk. Workers and guests interrupt their intimate moment as they arrive for the play.
Chekhov's setting of a stage on a stage tells audiences from the beginning of his play that The Seagull is no ordinary play. Treplev's stage creates a situation in which the play characters become more like their own audience because they themselves watch and are aware of the illusion of the theater. This is an tradition in the theater, presented repeatedly in Shakespeare's plays, such as Hamlet and A Midsummer Night's Dream. The stage on the stage is emblematic of the self-analysis and exploration of the self that the play will examine. This setting foreshadows major themes of the play such as the role of theater, art, and love in a person's life as well as man and self-evaluation and reinvention of his purpose in life.
Act One sets up several parallels that will run through the play. One such parallel are the love triangles. The love triangle between Medvedenko, Masha, and Treplev is established in the first moments of the play. Another motif that Chekhov establishes early on is class differences. He juxtaposes Medvedenko and Treplev. Medvedenko talks of his poverty as the source of his suffering while Treplev, who does not need to hold down a job and frets over his play production. His major concerns of surviving relate to philosophical, emotional, and spiritual fulfillment, not necessities like providing food, income, and shelter, which concern Medvedenko.