To be a 'commonsense realist' is to hold that perceptual experience is (in general) an immediate awareness of mind-independent objects, and a source of direct knowledge of what such objects are like. Over the past few centuries this view has faced formidable challenges from epistemology, metaphysics, and, more recently, cognitive science. However, in recent years there has been renewed interest in it, due to new work on perceptual consciousness, objectivity, and causal understanding. This volume collects nineteen original essays by leading philosophers and psychologists on these topics. Questions addressed include: What are the commitments of commonsense realism? Does it entail any particular view of the nature of perceptual experience, or any particular view of the epistemology of perceptual knowledge? Should we think of commonsense realism as a view held by some philosophers, or is there a sense in which we are pre-theoretically committed to commonsense realism in virtue of the experience we enjoy or the concepts we use or the explanations we give? Is commonsense realism defensible, and if so how, in the face of the formidable criticism it faces? Specific issues addressed in the philosophical essays include the status of causal requirements on perception, the causal role of perceptual experience, and the relation between objective perception and causal thinking. The scientific essays present a range of perspectives on the development, phylogenetic and ontogenetic, of the human adult conception of perception.