From the Mixed-Up Files of Mrs. Basil E. Frankweiler is quite a breezy read for an early reader. There's adventure galore, and the simple sentence structure and all the dialogue keeps the story (and the reader) moving along at a nice pace. There might be a few big words thrown in there—especially when Claudia's feeling a bit snobby about the finer things in life—but for the most part, this is a story designed for the young reader.