Depression is a common and devastating neuropsychiatric disorder, and a better understanding of its pathophysiology is needed to improve diagnosis, treatment and prevention. By considering the developmental dimensions of genetic and environmental factors, new insights have been found into the etiology and pathophysiology of depression. Specifically, we begin to understand how certain vulnerability factors affect the maturation of brain circuits involved in emotional function to increase the risk for depressive disorders later in life. These new findings might help us to better categorize and manage this complex disease.