Live ants are coming to Room 2B, and Harry gets to take care of them when they arrive. He'll get to help the teacher transfer all the ants to their new home in the classroom where everyone can watch them. Can trouble be far behind?

Horrible Harry falls in love with Song Lee, and Harry's best friend, Doug, can't stand all that mush.

It's almost summer vacation and the students in room 2B are having trouble concentrating on their butterfly project, until a frightening-looking new teacher comes to supervise the Suspension Room and Harry is sent there as punishment for unruly behavior.

When Horrible Harry starts third grade, he expects everything will be familiar. He is sure he will have the same teacher, the same class, and the same room. But when he walks through the door the first day, he discovers that the school is as unfamiliar as Mars! Soon Harry and the other students in Room 3B are sharing their souvenirs from the summer. Everyone is trying to read the cursive writing on the bulletin board. Some things haven't changed,...

Horrible Harry sets out to discover who Miss Mackle is going to marry, and he takes some risky moves to be the first one to know.

The students in Miss Mackle's third-grade class enjoy a day of Halloween surprises, including Harry's unusual costume.

All the students in Room 2B are getting ready for Christmas. They are excited and filled with holiday spirit. But when their teacher, Miss Mackle, sits down in her chair, it breaks, and she gets hurt! Now Miss Mackle has to spend Christmas in the hospital. The students don't feel like celebrating any more. It's up to Harry to think of a present that will cheer her up and bring the holiday mood back. Will Harry find a gift that is wonderful—and...

Working on a dragon project in Room 3B leads to a war between two good friends--Harry and Song Lee.

Miss Mackle's third graders share December holiday traditions --Christmas, Hanukkah, Kwanzaa, Three Kings Day, and Korean New Year-- with each other and with Harry's great grandfather, who has just moved to a nursing home.

When Horrible Harry's pet cat, Googer, sneaks a ride and gets into the school building, third-graders Harry and Doug have to catch him before anyone else does, which means going into some forbidden places.