Benjamin B. Lahey was born in 1945 in the United States. He is the Irving B. Harris Professor of Psychiatry at the University of Chicago and was President of the International Society for Research in Child and Adolescent Psychopathology. He received the U.S. National Academy of Neuropsychology research prize for his work on attention-deficit/hyperactivity disorder. He first conducted research on the effectiveness of behavior therapy with school children. He then created a reliable and valid assessment of psychological problems for large samples of children. He directed the American Psychiatric Association field trials on disruptive behavior disorders in children. With Rolf Loeber, he also created a longitudinal study of clinic-referred prepubertal boys with problems of hyperactivity and serious conduct problems: The Developmental Trends Study. He also created a large cohort of twins to study the genetic and environmental contributions to conduct disorder. Results led him and his colleagues to propose a hierarchical causal model of psychological problems in which he hypothesized a general factor of psychopathology that plays a central role. The key idea is that the causes and mechanisms of each dimension of psychological problems cannot be studied and understood separately; they are far too intertwined.