Romeo and Juliet first meet in Act I, scene 5. Until this moment, Romeo has been infatuated with the never-seen Rosaline. Yet when he glimpses Juliet for the first time, he is instantly in love. They exchange greetings in sonnet form, and even their very first words are words of love. They speak in religious terms, with Romeo as a "pilgrim" and Juliet as a "saint." However, Tybalt, Juliet's cousin, hears Romeo's voice and knows he is a Montague. This foreshadows the conflict between them later on.
All of this takes place at the Capulets' house, where Lord Capulet has decided to host a masquerade. Although Romeo was reluctant to go, preferring to mope about and sigh because of Rosaline, Benvolio convinces him to attend in disguise. On the way to the party, Mercutio livens up the atmosphere with his famous "Queen Mab" speech, injecting some humor into the tense drama.