Few areas of study have led to such close and intense interactions among computer scientists, psychologists, and philosophers as the area now referred to as cognitive science. Within this discipline, few problems have inspired as much debate as the use of notions such as meaning, intentionality, or the semantic content of mental states in explaining human behavior. The set of problems surrounding these notions have been viewed by some observers as threatening the foundations of cognitive science as currently conceived, and by others as providing a new and scientifically sound formulation of certain classical problems in the philosophy of mind. The chapters in this volume help bridge the gap among contributing disciplines-computer science, philosophy, psychology, neuroscience-and discuss the problems posed from various perspectives.