Cross-sectional national data indicate poor levels of treatment and control of hypertension. We identified factors that prospectively predict initiation of antihypertensive therapy and attainment of blood pressure control in the community. We included all Framingham Heart Study subjects examined between 1987 and 1999 who had untreated or uncontrolled hypertension (systolic > or =140 or diastolic > or =90 mm Hg) at a baseline examination and presented for follow-up examination 4 years later. Clinical covariates were examined for their association with initiation or control at follow-up. Among 1103 hypertensive participants who were untreated at baseline, 350 (31.7%) subjects were receiving therapy at follow-up, including 25.7% of subjects with stage 1 and 51.2% of those with stage > or =2 hypertension at baseline. Multivariate predictors of initiation of therapy included higher systolic and diastolic pressure, prevalent and interim cardiovascular disease, and left ventricular hypertrophy. Other cardiovascular risk factors did not predict initiation of treatment. Among 2475 hypertensive participants who were uncontrolled (treated or untreated) at baseline, 988 (39.9%) were controlled at follow-up. Prevalent cardiovascular disease and interim initiation of therapy predicted control; older age and higher baseline systolic levels predicted lack of control. These data provide estimates of longitudinal rates of treatment and control of hypertension in the community. It appears that global risk was not taken into consideration when making decisions for initiation of therapy. Greater emphasis is needed on achieving blood pressure control in all patients but particularly among older subjects and those with systolic hypertension.