This volume is an outgrowth of an invitational conference held in October 1991 on the main campus of Texas A&M University and sponsored by a grant from the Dean's Office of the College of Education. The expressed purpose of the conference was to allow researchers from too often dispa­ rate areas of research related to individual differences to come together and discuss their approaches to the topic, share ideas, and critique their differing paradigms to shorten the time it takes for researchers in parallel disciplines to discover advances that may aid their own work. We sought to bring together world-class psychometricians and statis­ ticians, cognitive scientists, and neuroscientists focused on the common theme of individual differences. Each reviewed advances in his or her own work that has clear implications for enhancing our understanding of indi­ vidual differences - from defining and partitioning variance components to modeling individual differences to structural and functional cortical variations that produce individual differences. The Chair of the Department of Educational Psychology at Texas A&M University, Bruce Thompson, took a lead role along with Victor L.