Our premise was that actions taken to reduce health risks are guided by the actor's subjective or common-sense constructions of the health threat. We hypothesized that illness threats are represented by their labels and symptoms (their identity), their causes, consequences, and duration. These attributes are represented at two levels: as concrete, immediately perceptible events and as abstract ideas. Both levels guide coping behavior. We interviewed 230 patients about hypertension, presumably an asymptomatic condition. When asked if they could monitor blood pressure changes, 46% of 50 nonhypertensive, clinic control cases said yes, as did 71% of 65 patients new to treatment, 92% of 50 patients in continuing treatment, and 94% of 65 re-entry patients, who had previously quit and returned to treatment. Patients in the continuing treatment group, who believed the treatment had beneficial effects upon their symptoms, reported complying with medication and were more likely to have their blood pressure controlled. Patients new to treatment were likely to drop out of treatment if: they had reported symptoms to the practitioner at the first treatment session, or they construed the disease and treatment to be acute. The data suggest that patients develop implicit models or beliefs about disease threats, which guide their treatment behavior, and that the initially most common model of high blood pressure is based on prior acute, symptomatic conditions.