The handbook was written with two types of readers in mind: those who are relatively new to functional neuroimaging and/or cognitive neuroscience, and those who are seeking to expand their understanding of cognitive and brain systems. It is our hope, and intention, that this unique combination of depth and breadth will render the book suitable for both the student and the established scientist alike. With a balanced blend of theoretical and empirical material, the handbook should serve as an essential resource on the functional neuroimaging of cognitive processes, and on the latest discoveries obtained through positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Indeed, in recent years the field of functional neuroimaging of cognition has literally exploded. From less than a dozen papers in 1994, the number of publications in this area increased to about 70 in 1995, and to more than 300 in 1999 (Cabeza & Nyberg, 2000, Journal of Cognitive Neuroscience, 12, 1–47). This handbook provides the reader with a comprehensive but concise account of this rapidly growing literature.