Richard E. Tremblay was born in Canada in 1944. He is Emeritus Professor of Pediatrics and Psychology at the University of Montreal (Canada) and Emeritus Professor of Public Health at University College Dublin (Ireland). He received the Stockholm Prize in Criminology and the John Paul Scott Award for lifetime contributions to research on aggression from the International Society for Research on Aggression. He participated in the creation of numerous longitudinal and experimental studies to unravel the early development of chronic physical aggression and to identify effective early preventive interventions. He systematically used an integrated bio-psycho-social approach. He initially showed that boys’ frequency of physical aggressions from kindergarten to adolescence decreased, rather than increased with age as would be expected from a social learning perspective. With a study starting in infancy, he then showed that infants start to physically aggress before the end of the first year after birth and that frequency of physical aggressions substantially increase between 8 and 42 months of age, followed by a universal decrease in physical aggression frequency until adulthood. He also initiated the Montreal experimental preventive intervention with physically aggressive kindergarten boys from low socio-economic environments, which showed significant reductions of substance abuse, school drop-out, juvenile delinquency, and adult criminality.