The play begins with a street brawl between two families: the Montagues and the Capulets. The Prince of Verona, Escalus, intervenes with his men and declares that the heads of the two families will be held personally accountable for any further breach of the peace. Later Count Paris, a young nobleman talks to Lord Capulet about marrying his thirteen-year-old daughter Juliet. Capulet demurs citing the girl's tender age, and invites him to attract the attention of Juliet during a ball that the family is to hold that night. Juliet's mother tries to persuade her daughter to accept Paris' courtship during this ball; and Juliet says that although she will make an effort to love him, she will not express love that is not there. In this scene Juliet's nurse is introduced as a talkative and humorous character, who raised Juliet from infancy.

In the meantime, Benvolio queries his cousin Romeo, Lord Montague's son, to find out the source of his melancholy. He discovers that it stems from an unrequited love for a girl named Rosaline, Capulet's niece. Upon the insistence of Benvolio and another friend Mercutio, Romeo decides to attend the masquerade ball at the Capulet house in hopes of meeting Rosaline. Alongside his masked friends Romeo attends the ball as planned, but falls in love with Juliet (forgetting about Rosaline) and she with him. Despite the danger brought on by their feuding families, Romeo sneaks into the Capulet courtyard and overhears Juliet on her balcony vowing her love to him. He makes himself known to her, and the two declare their love for each other and agree to be married. With the help of the Franciscan Friar Lawrence, who hopes to reconcile the two families through their children's union, the two are married secretly the next day.

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