In recent years, powerful new imaging technologies and other approaches have allowed scientists to track the development of the brain during childhood. These studies offer a way to understand how the intellectual abilities and behavioral maturity of children at various ages are rooted in the developing brain. Studies of the developing brain also offer the best possibility for understanding the origins of mental illnesses. Research suggests that vulnerability to mental illness—and resilience—is rooted in development. Both risk and resilience are shaped by genes and environment interacting together, through childhood and adolescence. Research can show how.