The Big Book of Concepts is the best book on concepts since George Lakoff's Women, Fire and Dangerous Things, published 15 years earlier. I am a professional cognitive scientist and I first read this book a number of years ago. I recently needed to look something up on infant concept formation, so I reread the chapter called "Concepts in Infancy," and was reminded just how good the book is. It is crammed with so much information that it has the potential for being as dry as dust, but, happily, it is loaded with clear examples, and is written in such a fluid style that you tend to keep reading, even after you've found the item or reference or example you were looking for. The book includes in-depth discussions of everything from theories of what constitutes a concept, to how they develop, to how they are related to words, and to the role of computational modeling in concept understanding (the succinct description of Nosofsky's Generalized Context Model, pp. 65-71, is one of the clearest, simplest descriptions of that model around). In short, for people interested in concepts and categorization, this book is a must-have for their library.