Oxytocin (OT) and vasopressin (AVP) play important reciprocal roles mediating and modulating social behaviors such as pair-bonding, attachment, sexuality and care-taking in animal models. In humans, the social role of OT and AVP has been examined primarily in small convenience samples in the laboratory. Because social isolation is associated in humans with higher all cause mortality, we measured urinary OT and AVP in a large sample of older community dwelling adults representative of the US population (57 – 85 years of age, N = 1882; National Social Life, Health and Aging Project). OT was associated with a complex of social characteristics and behaviors. OT levels were associated with marital status, higher at older ages in cohabitating unmarried women, but not married women. Marital status did not affect men. A range of negative psychosocial variables indicative of anxiety and social uncertainty were associated with lower OT, including feeling butterflies in one’s stomach, feeling tense or wound up, and feelings of uncertainty over demands and criticisms from friends. AVP, in contrast, was strongly associated with feelings of happiness over the life course, as well as having never been married. OT and AVP seem to play countervailing roles in the regulation of stable relationships among older adults in the US; AVP in the maintenance of greater happiness, and OT in the response to anxiety of uncertain social networks.