The Loooooongest Early Reader Chapter Book Series for Voracious Young Readers

Nate the Great (over 20 books!), by Marjorie Weinman Sharmat and Marc Simont
This entertaining series is great for any budding Sherlock Holmes, as young readers get the chance to solve the mystery along with Nate and his dog Sludge. Boy detective Nate can solve any case if he gathers all the facts and asks the right questions—that’s what makes him the world’s greatest detective. The black and white illustrations provide clues for readers, allowing them to use their logical thinking skills while reading.

The Adventures of the Bailey School Kids (over 50 books!), by Debbie Dadey, Marcia Thornton Jones and John Steven Gurney 
A personal favorite from my own childhood, this series was my go-to book at the bookstore. The kids at Bailey Elementary always seem to think they’ve encountered a mythical being. And with a town full of such strange grown-ups, who can blame them? With over 50 (!!!) books, there’s a whole world of mythical creatures for your kids to learn about. Is their teacher a vampire? Is their crossing guard a guardian angel? Read the books to find out!

A to Z Mysteries (over 25 books!), by Ron Roy and John Steven Gurney 
Another mystery series, the A to Z mysteries follows the adventures of three child detectives as they solve 26 mysteries (one for each letter of the alphabet). Dink, Josh, and Ruth Rose will delight young readers as they work together to help others and find clues in these entertaining reads. There are enough clues sprinkled throughout that some children may even find themselves solving the mystery first! And, if they finish all 26, they can move on to the A to Z Mysteries Super Edition, which follows the same characters. The author also wrote a spin-off series called Calendar Mysteries (one for each calendar month) and an unrelated mystery series called Capital Mysteries series, of which there are over 10.

Magic Tree House (over 25 books!), by Mary Pope Osborne
Jack and Annie are living the dream—they discover a mysterious tree house filled with books. And as it turns out, it’s a magic tree house that whisks them to the past. This fun series is as entertaining as it is informative, with plenty of historical tidbits. Last year, it celebrated 25 years with a new installment of the classic series, A Big Day for Baseball, for a total of 29 books in the original series. When your children finish devouring them, they can pick up the Magic Tree House Merlin Mission books, which follow the same characters but are slightly more advanced.

Mr. Putter and Tabby (over 20 books!), by Cynthia Rylant and Arthur Howard 
This story of friendship is the perfect starter series for kids new to chapter books. With few chapters, easy to understand language, and beautiful illustrations, these warm-hearted stories will make kids feel a little less lonely in the world. The author is no stranger to early reader series, either. She’s also the writer of the much beloved Henry and Mudge series, which has over 28 books, and the (small by comparison) Poppleton series with 8 books.

Katie Woo (over 30 books!), by Fran Manushkin and Tammie Lyon
Filled with gorgeous illustrations and excellent messages, this long running series is a hit with kids and adults alike. It follows Katie Woo, a relatable young girl who’s just trying to figure out how things work. From sickness to birthdays to bullying, Katie Woo confronts real-world issues with her trademark spunk and positivity, making her an excellent character for beginning readers who are also trying to make sense of the world around them.