This is an edited volume and, as such, is prone to certain strengths and weaknesses. Among the former is the array of contributors. All are prominent in the field, and all bring substantial research experience to their topics. These topics are, in turn, well balanced. Three chapters concern the physics and physiology thought to underlie the benefits of light; the remainder review the empirical evidence for efficacy in specific disorders. There is some redundancy in all of this but probably less than in most edited books. As is also true of most edited books, the coverage of the literature is less timely than that of journal articles generally. Some chapters here have no references beyond 1995, although several bring the reader into 1997.