The purpose of this study was to develop a culturally specific explanatory model (EM) of diabetes mellitus from the perspective of Mexican Americans living along the United States-Mexican bonier Kleinman's concept of EMs of illness was used as the theoretical orientation, and the grounded theory method was used to sample, collect, and analyze data. The Mexican Americans in this study described their perceptions of type 2 diabetes using the following constructs: causes, symptom, treatment, and social significance. Each of the components of Mexican Americans' EM contained elements of both the folk and the biomedical perspective. Susto (a fright or scare) was perceived to be the primary cause of diabetes, although participants also incorporated biomedical causes. Treatment included the use of both herbal and biomedical modalities. The use of herbal remedies was not well understood by the participants despite the fact that some used herbal therapies to control their diabetes.