Cluster analysis is a multivariate classification technique that allows for identification of homogenous subgroups within diverse samples based on shared characteristics. In recent years, cluster analysis has been increasingly applied to psychological and neuropsychological variables to address a number of empirical questions. This book provides an overview of cluster analysis, including statistical and methodological considerations in its application to neurobehavioral variables. First, an introduction to cluster analysis is presented that emphasizes issues of relevance to neuropsychological research, including controversies surrounding it use. Cluster analysis is then applied to clinical disorders that do not have an associated prototypical neuropsychological profile, including traumatic brain injury, schizophrenia, and health problems associated with homelessness. In a second application, cluster analysis is used to investigate the course of normal memory development. Finally, cluster analysis is applied to classification of brain injury severity in children and adolescents who sustained traumatic brain injury.