Sixteen-year-old Juno MacGuff discovers she is pregnant after a relationship with her friend Paulie Bleeker. She decides to give the baby up for adoption rather than have an abortion. With help from her friend Leah, Juno finds an adoptive couple, Mark and Vanessa Loring. Juno bonds more with Mark but decides to go through with the adoption. She later admits her love for Paulie and he supports her through the birth of their son, who Vanessa joyfully claims as her adoptive son.