The play begins with a street brawl between Montagues and Capulets. The Prince of Verona intervenes and declares that further breach of the peace will be punishable by death. Meanwhile, Count Paris talks to Lord Capulet about marrying his daughter, but Capulet is wary of the suit because Juliet is still only thirteen. Capulet asks Paris to wait another two years and invites him to attend a planned Capulet ball. Lady Capulet tries to persuade her daughter to accept Paris' courtship. In this scene Juliet's nurse is introduced as a talkative and humorous character, who raised Juliet from infancy. After the brawl, Benvolio talks with his cousin Romeo, Lord Montague's son, over Romeo's recent depression. Benvolio discovers that it stems from unrequited love for a girl named Rosaline, one of Lord Capulet's nieces. Persuaded by Benvolio and Mercutio, Romeo attends the ball at the Capulet house in hopes of meeting Rosaline. Romeo and Juliet fall in love, not knowing that they are on opposite sides of the feuding families. After the ball, Romeo sneaks into the Capulet courtyard and overhears Juliet vowing her love to him in spite of her family's hatred of the Montagues. Romeo makes himself known to her and they agree to be married.
With the help of Friar Lawrence, who hopes to reconcile the two families through their children's union, they are married secretly the next day. Juliet's cousin Tybalt, however, is offended that Romeo snuck into a Capulet ball and challenges him to a duel.