Substance abuse and addiction are preventable disorders that interfere with normal healthy functioning, contributing to physical and behavioral health problems, injuries, lost income and productivity, and family dysfunction. While substance use generally begins during the adolescent years, there are known biological, psychological, social, and environmental factors that contribute to the risk that begin accumulating as early as the prenatal period. This creates opportunities to intervene very early in an individual's life and thereby prevent substance use disorders-and, along with them, a range of other related behavioral problems-long before they would normally manifest themselves. This supplement to the second edition of NIDA's "Preventing Drug Abuse Among Children and Adolescents" reflects a growing body of research that has continued to accumulate showing that providing a stable home environment, adequate nutrition, physical and cognitive stimulation, warm supportive parenting, and good classroom management in the early years of a child's life can lead the child to develop strong self-regulation (i.e., emotional and behavioral control) and other qualities that protect against a multitude of risks and increase the likelihood of positive developmental outcomes. Positive effects of these interventions include delayed initiation and decreased use of drugs when the child reaches adolescence.