There are plenty of books around that tell you the "right" way to construct an English sentence. "Grammar: A Pocket Guide" certainly answered my questions about standard English usage, but it went beyond what I expected from a "pocket guide" by putting the whole issue of proper grammar into a broader context. The author comes at the subject from the perspective of her discipline, linguistics, which leads her to view various forms of usage as simply different from each other rather than "right" or "wrong." She clearly explains the standard forms of usage that are generally expected in a school or work setting, but at the same time, she provides fresh insight into the extraordinary flexibility and diversity of the English language. She also does an excellent job of demystifying the jargon of grammar (for a good example, take a look at Chapter 8 on the subjunctive). Add to that the author's approachable and personable voice, and you have a grammar book that is not just a valuable reference, but also a good read.