In social species, including our own, interactions with other members of the same species powerfully shape the environment that animals face each day. These interactions mediate the evolutionary costs and benefits of group living. Here, I will present our recent research on the impact of social interactions at the molecular and organismal levels. Using a 45-year data set from wild baboons in Kenya, we demonstrate that social adversity in early life combines with ecological pressures to profoundly shape individual survival and lifetime reproductive success. In both wild baboons and captive rhesus macaques, we also identify close ties between one dimension of social interactions—position in a dominance rank hierarchy—and gene regulation in the immune system. This signal is especially marked in male baboons and female rhesus macaques, and in the latter case, we show that social status causally alters the response to a model of bacterial infection. However, the relationship between dominance rank and gene regulation differs between baboons and rhesus macaques in key ways. Our results indicate that the effects of social status are contingent on how it is achieved and maintained, as well as its benefits for the organism. More broadly, our findings demonstrate that close ties between social adversity and survival have a long evolutionary history in the primate lineage, and that changes at the level of gene regulation contribute to this relationship.