The biocultural interchange between the Eastern and Western Hemispheres beginning in the late fifteenth century initiated an unprecedented adaptive transition for Native Americans. This article presents findings from the initial population biological study of contact in the central Andes of Peru using human skeletal remains. We test the hypothesis that as a consequence of Spanish colonization, the indigenous Mochica population of Mórrope on the north coast of Peru experienced elevated systemic biological stress. Using multivariate statistical methods, we examine childhood stress reflected in the prevalence of linear enamel hypoplasias and porotic hyperostosis, femoral growth velocity, and terminal adult stature. Nonspecific periosteal infection prevalence and D 30+/D 5+ ratio estimations of female fertility characterized adult systemic stress. compared to the late pre-Hispanic population, statistically significant patterns of increased porotic hyperostosis and periosteal inflammation, subadult growth faltering, and depressed female fertility indicate elevated postcontact stress among both children and adults in Mórrope. Terminal adult stature was unchanged. A significant decrease in linear enamel hypoplasia prevalence may not indicate improved health, but reflect effects of high-mortality epidemic disease. Various lines of physiological, archaeological, and ethnohistoric evidence point to specific socioeconomic and microenvironmental factors that shaped these outcomes, but the effects of postcontact population aggregation in this colonial town likely played a fundamental role in increased morbidity. These results inform a model of post-contact coastal Andean health outcomes on local and regional scales and contribute to expanding understandings of the diversity of indigenous biological variation in the postcontact Western Hemisphere. © 2008 Wiley-Liss, Inc.