There has been an explosion of interest in addressing social needs in health care settings. Some efforts, such as screening patients for social needs and connecting them to needed social services, are already in widespread practice. These and other major investments from the health care sector hint at the potential for new multisector collaborations to address social determinants of health and individual social needs. This article discusses the rapidly growing body of research describing the links between social needs and health and the impact of social needs interventions on health improvement, utilization, and costs. We also identify gaps in the knowledge base and implementation challenges to be overcome. We conclude that complementary partnerships among the health care, public health, and social services sectors can build on current momentum to strengthen social safety net policies, modernize social services, and reshape resource allocation to address social determinants of health.