Why does the science of brain development have such compelling influence on our thinking about children’s development? This question is explored in relation to an important Supreme Court decision concerning adolescent responsibility in which the findings of developmental neuroscience were influential but misleading. In considering this case, the chapter explores the concepts of neurorealism (i.e., brain images provide “visual proof” of the brain’s influence on mental processes) and neuroessentialism (i.e., brain processes are the material basis for mental processes). Then the chapter describes why we are – but should not be – neurodeterminists by showing how the brain and mind are mutually influential in development and that both are affected by experience. The chapter also describes the difficulties of attributing specific mental processes to particular areas of the brain, and considers the importance of context and culture in the development of brain and mind. The chapter shows that without due consideration of the multiple influences on the developing brain and mind, and careful examination of the contexts in which they develop, mistaken applications of developmental brain science are more likely. The clear and accurate communication of the science is thus crucial to public understanding and responsible policy applications.