This is it. This is the series every parent of a 5-7 year old should own. Mo Willems created something rare: books that kids genuinely want to read themselves, that teach reading skills without feeling like homework, and that model friendship in ways that actually stick.

The genius is in the simplicity—speech bubbles, expressive fonts (words get BIG when characters are excited!), and plots about everyday kid problems like waiting, sharing, and feeling left out. Gerald and Piggie are distinct personalities who balance each other beautifully, and kids see themselves in both characters at different times.

The box set with all 25 books is expensive but worth every penny if you have an early reader. These books get read dozens of times, acted out, quoted, and loved. Teachers use them. Librarians recommend them. Kids request them. That's the trifecta.

If you're building a young reader's library and can only buy one series, make it this one.