Through a misunderstanding, Junie B. thinks that her new baby brother is really a baby monkey, and her report of this news creates excitement and trouble in her kindergarten class.
Junie B. thinks first grade is a flop when her kindergarten friend Lucille prefers the company of twins Camille and Chenille and Junie B. needs glasses.
Junie B.'s journal entries start with Room One's stomach virus excitement, the first-grade Columbus Day play, and getting the part of the Pinta, the fastest ship.
After her first trip to a beauty parlor Junie decides she wants to work there, and she practices on her bunny slippers, her dog, and herself with disastrous results.
Junie B is very upset when a boy in her class plans to invite everyone except her to his birthday party, but her grandfather helps her deal with the situation.
Unable to compete with her friends' fancy clothes and running ability, irrepressible six-year-old Junie B. finds her own way to make the new boy at school like her.
Frustrated because the rules for her class's Pet Day will not let her take her dog to school, Junie B. Jones considers taking a raccoon, a worm, a dead fish, and other unusual replacements.
With Halloween approaching, Junie B. needs to find a costume that will scare off the real witches and ghosts that she believes will be out on the holiday.