It’s a horrible day for Harry: a classmate is calling him names; his library book is overdue; he’s last in line for a turn to be the Room 3B VIP. Worst of all, it’s cold and icy outside again, which means no outdoor recess. It’s all too much for Harry—he starts to go cuckoo! Fortunately, there is a solution to Harry’s problems . . . but it comes from a very unexpected source.

Will the best artist win? The art teacher asks the students of Room 3B to draw posters of things they love, and one of them will get to display his or her artwork on South School's brand-new TV show. Harry doesn't care about the contest. Mary, on the other hand, is convinced that her poster is the best, and she can't wait for her television debut. But if Mary's poster doesn't get selected, then she's going to make horrible trouble for Room 3B--especially Harry!

When the diamond on Miss Mackle’s engagement ring disappears, the kids in Room 3B are determined to help her find it—especially Harry. The third grade talent show is coming up, and he wants to show off his skills as South School’s greatest detective. Meanwhile, Doug has no idea what to do for his act. He can’t sing like Dexter, or dance like Ida, or solve mysteries like Harry. Now the best friends have to find both Doug’s talent and the teacher’s diamond, or else the talent show will be a horrible disaster for everyone!

Nearly every kid in Room 3B is trying to get picked for the South School Safety Patrol Squad—especially Harry. Harry wants a star badge just like his grandpa's, so he works extra hard to be the perfect student: hanging up his jacket neatly, organizing the crayons in rainbow order, and—his favorite part—cleaning up sticky noodles off the floor after lunch. But Doug thinks someone is taking the power of Safety Patrol too far, maybe even using it to cheat at the Spring Book Fair Raffle! This is Harry’s chance to stop the horrible bully and prove that he deserves a special star. Can he do it?

Horrible Harry says goodbye in the 30th anniversary finale of a beloved series! The last day of third grade is approaching fast, but a farewell to Room 3B isn't the only goodbye Doug has to say this year. Song Lee and Mary are busy preparing an end-of-year present for their favorite teacher, Mrs. Flaubert, but their excitement can't distract Doug from Harry's suspicious silence. When Harry finally admits that his family is moving to a whole other town, Doug can't believe his ears. How will he survive fourth grade without his best friend?! But Harry has a more pressing question: who's that moving in to the empty house across the street from him? And what could these new neighbors mean for their friendship?

Another fun mystery starring Horrible Harry, and this time he's calling the shots! Harry has always loved solving mysteries, and now his friends in Room 3B have learned to love it, too. So Harry challenges them to figure out what he has hidden in his giant, old suitcase. Led by a very determined Mary, the kids take turns solving clues and piecing the mystery together. Their hunt leads them from the classroom to the library, and even to Harry's grandfather's nursing home. Will they be able to solve Harry's mystery? Or will things go horribly wrong for the novice detectives?

A story about appreciating and preserving the environment in your own backyard. Doug thought he knew everything about his best friend, Harry . . . until he discovers that Harry has a secret hideout in the woods just outside of South School.Unfortunately, Harry can’t keep his hideout a secret much longer, because the land is going to be sold and turned into a big apartment building—unless he and the rest of the kids in Room 3B can save it. Harry has the idea to turn the lot into a nature center, and his friends want to help after he shows them the beautiful wildflowers, yellow spotted salamanders, and slimy tadpoles. But can Harry persuade the school board to agree, too? Or will his horrible fear come true: losing his hideout forever?

Mary is always neat and organized, while Harry is horribly messy. But even Mary’s carefully planned schedule can’t help when things go wrong at her own birthday party. The party is supposed to start with the kids from Room 3B taking an exciting train ride, but when their train is delayed not one . . . not two . . . but three times, Mary’s plan is completely ruined! She thinks the only thing that can make her feel better is cup after cup of sugary Island Punch—even after her mom tells her to stop. But what Mary doesn’t know is that Harry has his own wacky ideas for saving Mary’s big day. Can the kids still have fun even when nothing’s going the way it’s supposed to, or will this be the most horrible birthday ever?

Horrible Harry is at it again in a rollicking story of Field Day adventures, mishaps...and revenge! It’s one of the best days at South School: Field Day! That means bean bag tosses, relay races, and tug of war. When Mr. Deltoid announces students will pair up to compete for a mystery prize, Harry and Doug are determined to win. But at what cost? Harry's sneaky tactics leave Sid and Mary grumbling. They even claim he’s cheating. Harry insists he's playing fair and square. Doug doesn’t know what to think! He must prove his best friend is innocent before his classmates seek Field Day revenge. Can they win and play by the rules, or will the highlight of the year be a horrible disaster?