We humans are highly sensitive to our social environments. Our brains have special abilities such as empathy and social foresight that allow us to understand each other’s feelings and communicate in ways that are unique among all living organisms. Our bodies use internal chemical messengers – hormones and neurotransmitters – to help guide responses to our social worlds. Understanding this chemical language is important for many research questions in anthropology. For the past 25 years I have conducted a field study of child stress and family environment in a rural community in Dominica. The primary objective is to document hormonal responses of children to everyday interactions with their parents and other care providers, concomitant with longitudinal assessment of developmental and health outcomes. Results indicate that difficult family environments and traumatic social events are associated with temporal elevations of cortisol and morbidity risk. The long-term effects of traumatic early experiences on cortisol profiles are complex and indicate domain-specific effects, with normal recovery from physical stressors, but some heightened response to negative-affect social challenges.