Abstract
This Special Section of Child Development Perspectives highlights the contributions of developmental science to the study of substance use and disorder. It focuses on the specific question of how genetic, biological, and environmental factors vary in the way they interactively predict substance use and disorder over the course of development. The first three articles outline answers to this question that are emerging from the study of substance use disorder and contributing contexts, particularly the work on the externalizing or behavioral-undercontrol risk pathway to substance use disorder. The markers of risk and contextual variation are further integrated in the final contribution, which evaluates current evidence for this pathway to substance use disorder.