Doug discovers that though being Harry's best friend in Miss Mackle's second grade class isn't always easy, as Harry likes to do horrible things, it is often a lot of fun.

Follows the school activities of second-graders, Harry and Doug, as they participate in a secret mission to celebrate "Charlotte's Web," learn how to make green slime, and put on a skit warning about the dangers of smoking.

As Valentine's Day approaches, the students in Room 2B are preoccupied with kickball and a possible wedding between Horrible Harry and Song Lee.

Horrible Harry, the class clown of Room 2B, returns to the spotlight with the Purple People, mysterious beings that only he can see.

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.

Harry and his detective classmates try to find clues relating to a mysterious locked closet in Room 3B.