Flat Stanley was a surprising hit here, but mine really liked Wayside School at that age. Short chapters that stand individually, but are absolutely hilarious. He also reread Mr. Popper's Penguins over and over again. The Fudge series by Judy Blume was another gold mine. We listened to one on audio book and then I bought the rest and Stepped Readers are great at that stage -- illustrations on every page and larger or smaller amount of text per page, depending on the "step" level", so you can gauge according to his need.Books by Margaret Davidson are great at that age -- short, with some illustrations to keep going, and interesting helpful hints and non-fiction topics: Louis Braille Helen Keller Five True Dog Stories Nine True Dolphin Stories The Scholastic Branches series books might work well as a bridge into longer chapter books: Kung Pow Chicken (Marko) Notebook of Doom (Cummings) Eerie Elementary (Chabert) Looniverse (Lubar) Some early chapter book series ideas: Henry and Mudge (Rylant) Billy and Blaze (Anderson) Flat Stanley (Brown) The Littles (Peterson) Catwings (Le Guin) Secrets of Droon (Abbott) Dragon Slayers' Academy (McMullan) Nate the Great (Sharmat) Jigsaw Jones (Prellar)