Where I Lived, and What I Lived For (Penguin Great Ideas)

The other reviewer is right that this book contains limited material from Walden. But that's precisely what makes it so useful. If you're interested in the full Walden experiment, with lengthy narratives on bird-watching and ditch-digging and any number of other things, by all means read Walden. However, for those who are simply interested in the philosophy of simple living and want to read shorter essays that get at the heart of it, this is an excellent selection. I fully recommend it.