Long ignored as not feasible, the search for the neural correlates of consciousness is now one of the most popular pursuits in neuroscience. There is a well-established community of scientists who write papers and hold conferences on this topic. Over the last 15 years Christof Koch and his collaborator, the late Francis Crick, have enlivened and sometimes exasperated this community with a series of proposals concerning the neural correlates of consciousness. However, work on the neural correlates of consciousness has been not only theoretical. In the last few years many well-motivated and well-designed experimental studies have been published, made possible, in part, by the rapid development of neuroimaging. One of the best things about Koch’s book, and one that distinguishes it from the many previous books on the neural correlates of consciousness, is that many of these experiments, particularly those relating to the visual system, are discussed in some detail.