This work investigates the philosophical, empirical, and theoretical bases on which a cognitive neuroscience of consciousness can be founded. The research questions reviewed include: Does perception occur without awareness? Can the neural bases of perceptual awareness be visualized with brain-imaging methods? What do unilateral neglect and extinction tell us about conscious and unconscious processing? What is the contribution of brainstem nuclei to conscious states? How can we identify mental processes uniquely associated with consciousness? An introductory chapter proposes a theoretical framework for building a cognitive neuroscience of consciousness, and two concluding chapters evaluate the progress made so far.