The Sustainable Development Goals (SDGs) provide a historic opportunity to implement at scale interventions to promote Early Childhood Development (ECD). While the evidence base for the importance of ECD has grown, the research is distributed across sectors, populations, and settings with diversity noted in the scope and focus. In this paper, we provide a comprehensive updated analyses of ECD interventions across five sectors: health; nutrition; education; child protection; and social protection. Our review concludes that to make interventions, successful, smarter and sustainable, they need to be implemented as multi-sectoral intervention packages anchored in "nurturing care". The recommendations emphasize that intervention packages should be applied at developmentally appropriate times during the life-course, target multiple risks, and build on existing delivery platforms for feasibility of scale-up. While interventions will continue to improve with the growth of developmental science, the evidence is now strong that parents, caregivers, and families need to be supported in providing nurturing care and protection for young children to achieve their developmental potential.