A number of avenues of research indicate that neurobiological abnormalities may be involved in eating disorders. An important component of this may be some form of dysfunction in cognitive processing. The aim of this book is to review the results and implications of previous research into neuropsychological function in Eating Disorders (ED), focusing on the diagnoses of Anorexia Nervosa (AN) and Bulimia Nervosa (BN). Published articles on this topic, uncovered in a recent systematic literature search, are summarised here in a table format, allowing the straightforward comparison of materials, methods and results across studies. Whilst providing insight into potential areas of cognitive dysfunction in this clinical group, the neuropsychological data that exists for eating disorders is somewhat unclear. A number of methodological limitations are inherent in this literature; with issues ranging from sample characteristics to study design and the variety of tests employed, thus restricting the conclusions that may be derived. Suggestions as to how these limitations may be overcome and potential directions for future research are discussed accordingly. We advocate the adoption of a hypothesis driven approach to explore neuropsychological processing in Eating Disorders, the utility of which has been confirmed in the ongoing work of our department. Based on clinical observation and personality research, our hypotheses with regards to reduced cognitive flexibility in individuals with AN have consistently been endorsed. Neuropsychological research has both important theoretical and clinical implications, advancing understanding with regards to aetiology and phenotypes of disorder. The knowledge derived from hypothesis driven neuropsychological studies may be applied practically in research and treatment settings, with the potential to initiate the development of innovative treatment interventions, as has been seen with other psychiatric disorders.