Much of what we say is never said aloud. It occurs only silently, as inner speech. We chastise, congratulate, joke, and generate endless commentary, all without making a sound. This distinctively human ability to create public language in the privacy of our own minds-to, in a sense, "hear" ourselves talking when no one else can-is no less remarkable for its familiarity. And yet, until recently, inner speech remained at the periphery of philosophical and psychological theorizing. This volume, comprised of chapters written by an interdisciplinary group of leading philosophers, psychologists, and neuroscientists, displays the rapidly growing interest among researchers in the puzzles surrounding the nature and cognitive role of the inner voice. Questions explored include: the aids and obstacles inner speech presents to self-knowledge; the complex relation it bears to overt speech production and perception; the means by which inner speech can be identified and empirically assessed; its role in generating auditory verbal hallucinations; and its relationship to conceptual thought itself.