This study was designed to pursue three objectives: 1) investigate the impact of culture change on children and adolescents in Western Samoa; 2) introduce a cross-cultural perspective to studies of psychosocial stress and immune function; and 3) evaluate the utility of minimally invasive methods for assessing immune function. Seven hundred sixty individuals between the ages of 4 and 20 years were recruited from three distinct geographic regions within Western Samoa that differ in degree of westernization. Finger prick samples of whole blood were collected from each individual and analyzed for antibodies against the Epstein-Barr virus (EBV; an indirect marker of cell-mediated immune function) and C-reactive protein (a nonspecific marker of current infection). After controlling for age, sex, and current infection, EBV antibody levels were significantly elevated in urban Apia and rural Upolu, indicating lower levels of cell-mediated immune function. The results suggest a higher degree of psychosocial stress in these regions, possibly due to exposure to westernizing influences. Am. J. Hum. Biol. 12:792-802, 2000. Copyright 2000 Wiley-Liss, Inc.