Blood pressure increases with age, and over time, reaches proportions consistent with clinically defined hypertension in some individuals. The age-dependent increase in blood pressure starts in mid-childhood and accelerates during puberty and in the post-pubertal period. Thus, mechanisms for the development of hypertension are likely present at an early age. The National Heart, Lung, and Blood Institute sponsored the 'Workshop on Juvenile Hypertension' in May 1983. The Workshop conclusions were that although a great deal had been accomplished in the past decade, research in juvenile hypertension had slowed and little effort was evident in some important areas of the field. They noted especially the paucity of effort in research relating to mechanisms of blood pressure regulation and elevation, to clinical management of the hypertensive state, and to identification of the prehypertensive state. Based on the recommendations of the Workshop, this study was initiated in response to a Request for Applications on 'Juvenile Hypertension and the Prehypertensive State' released by the NHLBI in October 1984.