This study examines problems involved in the management of chronic illness and disability in cross-cultural contexts. It specifically looks at conflicts between different belief systems and different discourse practices in cross-cultural communication between Tohono O'odham (Pagago) families of children with disabilities and non-Indian service providers. The discourse practices through which cultural knowledge is represented in face-to-face interaction, and the range of beliefs and practices which constitute cultural knowledge, are investigated sign ethnographic methods which emphasize a discourse-centered study of meaning and interaction. Utilizing information from participant observation, open-ended interviews, and naturally-occurring speech from a variety of interactional settings, the research focuses on both inter- and intra-cultural variation in knowledge and discourse. The major findings are: (1) a system of beliefs and practices about cause, prevention and treatment of serious illness exists in O'odham communities which differs significantly from the biomedical system within which medical and educational services to children with disabilities is provided; (2) intracultural variation exists in O'odham communities between language and knowledge held by specialists and lay people; and (3) the major genres used by O'odham people to provide information differ significantly from the formats routinely used by service providers to elicit information.