I read this with my 4 and 6 year old daughters. The book is filled with colorful photos and crazy facts. I would say that my 6 year old understood about 3/4 of the book. There were a few concepts that she couldn't quite understand but it didn't bother her in the least. I was always a fan of Ripley's as a kid and it was fun to share that with my kids. They are eager to start reading the second book in the series.