Hypertension (HTN) is a major health problem in the United States placing some 58 million Americans at increased risk for stroke, myocardial infarction, kidney failure, and peripheral vascular disease. In addition, HTN is associated with subclinical changes in the heart (e.g., left ventricular hypertrophy) and in the brain (e.g., impairments of cognitive function). Although pharmacologic management of HTN is often effective, medications are not without complications and untoward side effects. Consequently, there has been a great deal of interest in the development and application of behavioral treatments for the management of HTN. The present study has three long term objectives. The first is to evaluate the efficacy of two behavioral interventions -- aerobic exercise and weight management -- in reducing blood pressure in men and women with mild HTN; the second is to examine the mechanisms by which blood pressure is reduced; and the third is to investigate the effects of behavioral treatments on cognitive performance and related aspects of quality of life. Two hundred unmedicated subjects with mild HTN will be randomly assigned to 6 months of mild-moderate aerobic exercise, moderate-intensive aerobic exercise, moderate exercise combined with weight management, intensive exercise combined with weight management, or a waiting list control group. Subjects will undergo comprehensive evaluations at baseline and at 6 months. Measurements of blood pressure will be obtained in the clinic, during everyday life using ambulatory blood pressure monitoring, and during physical exercise and mental stress testing. Blood pressures will also be obtained at 1 year follow-up. In order to examine potential mechanisms responsible for blood pressure changes, subjects will undergo glucose tolerance testing, studies of heart rate variability, and hemodynamic and neuroendocrine assessments. Because hypertension has been shown to be associated with measurable changes in cognitive function, which may be reversible when blood pressure is normalized, subjects will also complete a neuropsychological assessment battery along with psychometric testing. Finally, the clinical significance of the blood pressure changes will be determined by repeat cardiac echocardiography, as well as by repeated blood pressure testing at baseline, 6 months, and 1 year followup. The information obtained from this study will have important practical significance by determining the efficacy of exercise and weight reduction in lowering blood pressure in men and women with mild hypertension, and by assessing the clinical importance of these changes. Moreover, the study has important scientific significance by clarifying the mechanisms that may be responsible for the blood pressure reductions.