Pretty darned definitive Plenty of useful examples, including counter-examples Shows how to migrate existing code, not just start from scratch Scriptaculous labs are excellent, and are available for download Okay, all the labs are excellent JavaScript haters beware! Prototype, Scriptaculous, and yes, this excellent book about these two JavaScript libraries, could change your mind. After reading Prototype and Scriptaculous In Action, you are in danger of saying to yourself, "Hey, I'd like to try some of this stuff out," and, before you even realize it, you're writing JavaScript, getting stuff done, and maybe even enjoying it.