Noncompliance with medical instructions is a major problem in health care. In areas of the world where traditional and Western systems co-exist, failure to follow medical directives has been attributed to the conscious rejection of Western medical beliefs and values by the indigenous population. This study provides evidence that the absence of shared concepts between practitioners and patients may impede even willing compliance. When patients do not possess the background knowledge, or schemata, undergirding the Western practitioners' conclusions and proposed treatment, they are unable to fully understand what is communicated because they lack the conceptual framework for integrating and holding the information presented. Matched groups of Australian Aboriginal and American women heard and recalled two stories incorporating Aboriginal and Western conceptions of illness and treatment. Analysis of the recall protocols reveals the effect of culture-based schemata on comprehension of the two stories. Implications for health care delivery are discussed.