Four-year-old Ramona has an imagination that makes her a menace to everyone around her, particularly her older sister, Beezus.

Ramona's year in third grade is highlighted by the arrival of Howie's rich uncle, a change in her after-school situation, a surprise wedding, a death and a new arrival in the family, and her father's getting a job.

Ramona Quimby expects fourth grade to be the best year of her life; and although things do not go just as she had hoped, she still manages to have her share of adventures.