A robust body of scientific evidence has indicated that being embedded in high-quality close relationships and feeling socially connected to the people in one's life is associated with decreased risk for all-cause mortality as well as a range of disease morbidities. Despite mounting evidence that the magnitude of these associations is comparable to that of many leading health determinants (that receive significant public health resources), government agencies, health care providers and associations, and public or private health care funders have been slow to recognize human social relationships as either a health determinant or health risk marker in a manner that is comparable to that of other public health priorities. This article evaluates current evidence (on social relationships and health) according to criteria commonly used in determining public health priorities. The article discusses challenges for reducing risk in this area and outlines an agenda for integrating social relationships into current public health priorities. (PsycINFO Database Record