Consciousness is, perhaps, the aspect of our mental lives that is the most perplexing for both philosophers and psychologists. Indeed, it sometimes seems to defy rational enquiry. However, the last few years have witnessed a resurgence of interest in this difficult, yet fascinating, topic. This collection of psychological and philosophicial essays, many of which are published here for the first time, provides a state-of-the-art survey of recent work. The psychological essays have in common a concern with the functional effects of consciousness on behaviour. The philosophical essays distinguish several different notions of consciousness, and address the question of whether phenomenal consciousness - the what it is like aspect of experience - necessarily eludes a physicalist or functionalist description of the world. The essays should be of interest to postgraduates and researchers in cognitive psychology and philosophy of mind.