Unlimited Squirrels Books in Order
Part ofMo Willems Books in OrderExplore the Unlimited Squirrels books by Mo Willems in order, with quick summaries, series background, and the best place to start with Zoom and friends.
Last updated: January 13, 2026
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Publication Order
5 books
The FRUSTRATING Book!
by Mo Willems
2022
Zoom Squirrel wants to experience brand-new emotions, and his squirrel pals are ready to help. But not every feeling is fun, especially frustration. A comic-style early chapter that makes room for big feelings and lots of jokes.
Guess What!?
by Mo Willems
2021
Zoom Squirrel is counting down to a trip to the beach and wants everyone to guess his big news. The closer it gets, the more nervous he becomes about what the beach will actually be like. A comic-style early chapter about anticipation.
I Want to Sleep Under the Stars!
by Mo Willems
2020
Zoom Squirrel wants to sleep outside under the stars, and he cannot stop talking about it. Excitement turns into worry as the night gets closer. A comic-style early chapter about trying something new, with plenty of squirrel chaos.
Who is the Mystery Reader?
by Mo Willems
2019
Zoom Squirrel is sure there’s a mystery to solve: who is the secret mystery reader at school? Zoom gathers clues, makes wild guesses, and drags his friends into the case. A comic-style story about curiosity and teamwork.
I Lost My Tooth!
by Mo Willems
2018
Zoom Squirrel has lost a tooth, and the whole squirrel crew has BIG thoughts about what should happen next. The story turns tooth drama into comic chaos, with jokes, asides, and a surprisingly sweet look at growing up.
Series background & context
The Unlimited Squirrels books are comic-style early chapter books starring Zoom Squirrel and a very opinionated crew of squirrel pals. The format is part story, part sketchbook, and part “you’re in the joke with us,” which makes them a great fit for kids who are ready for longer books but still love pictures on every page.
Zoom is the kind of character who enters a scene at full speed. He’s excited about everything, certain he’s right, and completely willing to announce his feelings in all caps. The other squirrels, and the reader, get pulled along for the ride as he tries to understand something new.
The squirrels take everything very seriously, which makes it funnier.
Each book has a clear theme that kids already care about, and the plot keeps circling back to it in different ways. I Lost My Tooth! takes on the drama of a missing tooth and all the expectations that come with it. Who is the Mystery Reader? turns a school moment into a detective case, as Zoom tries to figure out who is secretly reading to the class. I Want to Sleep Under the Stars! is about the excitement, and nerves, of trying an outdoor sleepover.
Guess What!? is built around anticipation. Zoom can’t stop talking about an upcoming trip to the beach, and the countdown is almost as intense as the trip itself. Later, The FRUSTRATING Book! zooms in on emotions, as Zoom and his pals explore what it feels like to have brand-new feelings you don’t totally enjoy.
The books are designed for kids who like to participate. Pages mix panels, big captions, quick jokes, and little asides that feel like the squirrels are talking directly to you. You’ll also see playful “extras”, short lists, mini-quizzes, and quick facts that keep the pace moving and give kids a breather between story beats.
Under all the silliness, the series is pretty kind about learning. Zoom doesn’t always handle a new situation gracefully, but his friends stick around, and he keeps trying. That makes the books feel like a safe place to practice reading and practice feelings at the same time.
You’ll get the most out of the series if you start at the beginning and read in order, because the friendships and running jokes build from book to book. But each story also stands on its own, so if a kid is obsessed with mysteries, camping, or the beach, it’s easy to jump in and then backfill later.
Edited by
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