Adolescent substance use is a significant predictor of future addiction and related disorders. Understanding neural mechanisms underlying substance use initiation and frequency during adolescence is critical for early prevention and intervention. A novel study in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, published by Elsevier, shows that by tracking year-to-year changes in brain connectivity underlying cognitive control, the ability to flexibly use goals to guide behavior and overcome habitual responses, data can predict when an adolescent is at high risk of starting to use substances, an important message for early prevention.