A number of small to moderate-sized randomized clinical trials of non-pharmacologic intervention in hypertension have been initiated during the past 5 years with NHLBI support. The Hypertension Prevention Trial (HPT) was the largest program studying the effectiveness of intervening in a non-hypertensive population. The HPT was a feasibility study to establish the ability to enroll in sufficient numbers men and women with diastolic blood pressure of 78-89 mm Hg; to determine if dietary intervention alone could achieve sustained weight reduction, and/or a decrease in sodium intake, or an increase in potassium intake along with sodium reduction in these subjects; and to study the effects of the interventions on blood pressure. If feasibility were demonstrated, the plan was to conduct a full-scale trial with incidence of frank hypertension as the outcome measure.