This book is concerned with three domains of child development that collectively contribute to a substantial proportion of troubling behaviors in the pediatric population. Specifically, these are spoken language, school achievement, and behavior disorders. A subtext in this book that can be found in several chapters pertains to the associations that appear among these. Although this book is not committed to any particular viewpoint regarding the basis for the relationships among these behavior domains, many of the chapters support the existence of an association among these and the comorbidity of deficits in each area. For many clinicians, the co-occurrence of these problems may be so common as to stifle curiosity over its clinical and theoretical implications; therefore, this book serves a valuable purpose by highlighting the association and the possible shared and unique causes of these deficits. This interest in the joint occurrence of these deficits by the editors is no doubt motivated by the fact that they have maintained a longitudinal study of a population sample of children in Ottawa that has provided some of the strongest empirical support for this association. In the spirit of the Ottawa study, the editors have included contributions by several authors who have conducted similar epidemiologic and genetic work in attention deficit hyperactivity disorder and reading disorder as well as spoken language disorder.