This article provides an update on advances in both developmental and intervention science that have occurred in the field of early intervention for children with developmental delays in the past decade. From the perspective of developmental science, findings related to multiple and reciprocal pathways of influence on the development of children with delays that can inform early intervention practice are discussed. This is followed by a review of two prominent lines of early intervention research: promoting children's development by enhancing parent-sensitive responsiveness and improving children's cognitive and social outcomes in inclusive preschool settings. Merging policy initiatives with our knowledge of developmental processes is discussed as the key to accelerating progress in the development of comprehensive early intervention systems.