The control of blood pressure (BP) for patients with hypertension on medications has been elusive, despite the availability of evidence-based nationally recognized guidelines for treatment and 30 years of research addressing this. At present less than 50% of patients with known hypertension are adequately controlled. If BP control could be improved, significant decreases in cardiovascular morbidity and mortality would occur. We propose to conduct a randomized controlled trial of the effectiveness of applying the Chronic Care Model (CCM) to improve hypertension control. We will identify a cohort of Group Health Cooperative patients with hypertension on anti-hypertensive medications, who have access to the Internet and E-mail, and who have poorly controlled blood pressure (BP > 140/90). Subjects willing to participate will be randomly assigned to one of three intervention arms: Group-1 (UC) will receive usual care for their hypertension. This includes access to secure Intranet services already available at GHC (including a health library, messaging, and prescription refill services); Group-2 (BPM), will additionally receive home blood pressure monitors, instruction on their use, and a proficiency training session on Web-based communication; or Group-3 (BPM+RX), who will receive all of the above plus planned and proactive, self and care management support provided by clinical pharmacists via the Web. Our study hypothesis is that BPM+Rx will prove to be more efficacious than UC or BPM in improving the following primary outcomes: (1) change in mean diastolic, systolic, and the combined average of diastolic and systolic blood pressure and (2) proportion of patients with adequately controlled blood pressure (defined as a BP of equal to or <140 mmHg systolic and equal to or <90 mmHg diastolic).