When his friend Doug is infested with head lice and Mary convinces everyone to stay away, Harry and his other friend Song Lee stand by Doug and declare war on the bugs in this 35th installment.

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?

After four days in a row of indoor recess, Miss Mackle's students are bored-until Harry decides to solve the biggest mystery ever in Room 3B! There's a locked closet in the classroom that's been sealed off for years, and he wants to know what's inside. So Harry drafts Doug, Song Lee, and the rest of the class to help him investigate. Their search reveals many surprises-from a hidden trapdoor to...eyeballs! What secret treasures does the closet hold? Is it something more horrible than even Harry can imagine?

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?

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.

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.

Harry's in love, and his best friend, Doug, is disgusted -- Harry won't even throw snowballs at girls anymore. Will Harry ever go back to being his horrible self?"Kline captures perfectly the crowd scenes and private moments in the classroom."-- Booklist