Neuroimaging provides a non-invasive window into brain development. Such studies have identified important maturational milestones from age 10 to the early 20s, which with cognitive and emotional maturation, allows for a successful transition from dependence to independence. Healthy neuronal development is notably susceptible to alcohol and drug use and, therefore, has a lifelong influence on mental health and behavior. Accordingly, the Neurodevelopmental Laboratory on Addictions and Mental Health (NLAMH) investigates the overlap between brain development, substance use, and mental illness, perhaps helping to explain clinical symptom onset, e.g., depression and anxiety. Together with our adolescent work, we are investigating the consequences of emerging adult (18-24yrs) binge drinking on brain structure and chemistry to probe neurobiology underlying “What were you thinking?” — brain mechanisms associated with impulsive and risky behaviors. We also are investigating brain chemistry, mood and cognition in depression. Collectively, we aim to identify who’s at greatest risk for addiction and psychiatric disorders.