We live in a world that is largely socially constructed. Empathy–the ability to share the emotional states of others–is crucial to our emotional and social lives. Empathy and empathy-induced altruism not only offer crucial benefits to individuals whose needs elicit empathic concern, but can also profoundly impact the mental and physical well-being of the altruistic helper. Deficits in detecting and responding to the emotions of others are prominent symptoms in many psychiatric disorders. However, the neural mechanisms underlying empathy remain largely unknown. Using state-of-the-art, multidisciplinary approaches, our central goal is to make groundbreaking discoveries on the molecular, cellular, and neural circuit basis for empathy and empathy-related behaviors. Our goal represents an exciting new frontier in behavioral, social, and systems neurosciences and will generate major scientific impacts, with important social and clinical implications.