During the past decade a diverse group of disciplines have simultaneously intensified their attention upon the scientific study of emotion. This proliferation of research on affective phenomena has been paralleled by an acceleration of investigations of early human structural and functional development. Developmental neuroscience is now delving into the ontogeny of brain systems that evolve to support the psychobiological underpinnings of socioemotional functioning. Studies of the infant brain demonstrate that its maturation is influenced by the environment and is experience-dependent. Developmental psychological research emphasizes that the infant's expanding socioaffective functions are critically influenced by the affect-transacting experiences it has with the primary caregiver. Concurrent developmental psychoanalytic research suggests that the mother's affect regulatory functions permanently shape the emerging self's capacity for self-organization. Studies of incipient relational