This study will examine the biological response to acculturative stress in the context of profound and rapid social change. The field-setting for this project is the eastern coast of the Yucatan Peninsula, Mexico. Since the early 1970's, this area has undergone a massive, planned development in response to a growing international tourism industry. As such, many indigenous Yucatec Maya have been drawn into the world economy. In the resort environment, gender, social, and work roles are especially vulnerable to change (Daltabuit 1994; Thomas and Pi-Sunyer 1994; Pi-Sunyer and Thomas 1997), with resultant challenges to mental and physical well-being. However, little work, either in anthropology or psychology, has addressed within- population variation in the biological response to acculturative stress. This project builds on previous work on the relationship between culture change and biology (measured through blood pressure and heart rate, urinary catecholamines, plasma cortisol and antibodies to Epstein-Barr virus-an indirect measure of immune function) by explicitly addressing intracultural variation in the stress response. Particular attention is paid to sex-differences in the definition of, and response to, psychosocial stress; the effect of group normal on the individual stress response, and the causal relationship between psychosocial stress, immunity, and infectious disease in a natural setting.