These studies examine children's understanding of the causes of illness cross-culturally. In Study 1, European- and Vietnamese-American 4- to 5-year-olds, 6- to 7-year-olds, and adults were asked to make causal attributions for a series of illness related stories. In Study 2, European- and Vietnamese-American 6- to 7-year-olds and adults were asked about the causes and remedies of illness. The results show that biological causality was the dominant form of reasoning about illness across the different ages and cultural groups, although there was some acceptance of magical causality among the Vietnamese-Americans (children and adults) and the European-American children. These results are discussed in terms of the coherence of illness beliefs.