Pam Dennison is perhaps one of the best authors in terms of presenting positive training in an understandable way, that shows clearly why it works and how it fits naturally into a dog's "culture." I also love that she included not just one, but two chapters on body language - sorely lacking in many books. This one has knocked a couple other recommended reads a bit lower on my list. More approachable than Pat Miller (an excellent trainer but too much train-of-thought in her books) and less technical than Pamela Reid (excellent read if you want more depth, tho), anyone can use this tool to create a wonderful relationship with a willing, eager-to-learn companion.
This book is not for the more challenging issues. It is mostly manners and prevention - the basics. Pair it with Outwitting Dogs, however, and you have all you need to tackle most* issues (*barring aggression, which should be handled with the help of a behaviorist who uses counter-conditioning and desensitization).