In this volume, six leading cosmologists provide a current "state of the universe" report: what we have learned about its nature, but also what pieces are still missing from the cosmic puzzle. The roster of contributors reads like a Who's Who of modern cosmology: A. P. Lightman, Robert P. Kirshner, Margaret J. Geller, Vera C. Rubin, Alan Guth, and James Gunn. The book is an excellent overview of the big questions facing modern cosmology. It does not require a background in physics, so any lay reader who appreciates astronomy and the study of the cosmos will enjoy this lively discussion.