Advances in neuroscience allow researchers to uncover new information about the social brain in infancy and early childhood. In this article we present state-of-the-art findings about brain functioning during the first 3 years of life that underscore how important social interactions are to early learning. We explore learning opportunities that occur during everyday interchanges between adults and infants and how these influence the brain. We also examine longitudinal data to understand how children's earliest social interactions set the stage for school readiness and lifelong learning.