Even before COVID-19, it was well known in psychological science that people’s well-being is strongly served by the quality of their close relationships. But is well-being also served by social contact with people who are known less well? In this article, we discuss three propositions that support the conclusion that the benefits of social contact also derive from interactions with acquaintances and even strangers. The propositions state that most interaction situations with strangers are benign (Proposition 1), that most strangers are benign (Proposition 2), and that most interactions with strangers enhance well-being (Proposition 3). These propositions are supported, first, by recent research designed to illuminate the primary features of interaction situations. This research shows that situations with strangers often represent low conflict of interest. Also, in interactions with strangers, most people exhibit high levels of low-cost cooperation (social mindfulness) and, if the need is urgent, high levels of high-cost helping. We close by sharing research examples showing that even very subtle interactions with strangers yield short-term happiness. Broader implications for COVID-19 and urbanization are discussed.