Act 1 introduces the reader to the central conflict between the House of Capulet and the House of Montague. Two Capulet servants pick a fight with Montague servants, which quickly escalates and draws in Benvolio from the Montagues and Tybalt from the Capulets. Eventually Lord Capulet and Lord Montague themselves arrive, but the melee desists at the command of Prince Escalus.

Benvolio then attempts to comfort his cousin Romeo, who is distraught over his unrequited love for Rosaline. On a different street, the nobleman Paris informs Capulet that he would like to marry Capulet's daughter Juliet. Capulet asserts that Juliet is too young for marriage yet, but agrees to throw a feast at which Paris might begin to court her. Capulet dispatches his servant Peter to invite people to the feast. Peter invites Benvolio and Romeo without knowing they are Montagues.

Before the feast begins, Lady Capulet takes Juliet aside and strongly suggests to her that she should start thinking about marriage, or more precisely, marriage to Paris. Meanwhile, Benvolio, Romeo, and their friend Mercutio make their way to the feast wearing masks as disguises. Romeo informs the other two that he had a dream which informed him that going to the feast would be a bad idea. He believes it will begin a chain of events that will lead to his untimely death. Nevertheless, Benvolio and Mercutio manage to raise his spirits and ease his doubts by the time they arrive.

Inside the feast, Romeo lays eyes on Juliet and immediately forgets about Rosaline. He approaches her, touches her hand, and utilizes religious metaphors in order to convey that he views Juliet as a saint who can absolve him of his sin. This absolution can only come in the form of a kiss, which Juliet assents to. Their moment of bliss is interrupted when Juliet's Nurse arrives. Before the night ends, Romeo and Juliet both learn through the Nurse that they have kissed a member of the rival house. Before he moves to Act 2, Shakespeare has planted the seeds for the conflict that will dominate the rest of the story line.