Untreated elevated blood pressure causes kidney damage and ultimately leads to kidney failure necessitating dialysis or transplantation. While kidney failure caused by hypertension is an important problem for the entire US population, it is of even greater concern for African Americans who are up to 18 times more likely that hypertensive Caucasians to suffer kidney damage severe enough to require dialysis. Previous clinical trials evaluating benefits resulting from the treatment of hypertension have focused largely on heart disease and stroke, for which antihypertensive drug treatment is clearly proven to be beneficial. For kidney disease, although control of blood pressure is presumed to be of benefit, the ideal level to which blood pressure should be reduced and the possible different benefits of the various drug classes are less well defined. Particularly vexing is the apparent lack of benefit for many African Americans with incipient kidney disease in whom kidney failure progresses despite apparently adequate blood pressure control. The current study, the African American Study of Kidney Disease and Hypertension (AASK), aims to find the best treatment strategy for preventing kidney failure in African Americans. The study design includes two different target levels of blood pressure control (corresponding to the usual level of control and to a more aggressive standard) each of which is achieved with three different antihypertensive medication regimens. The primary study outcome is an assessment of the rate of change in renal function in each of the six intervention groups. Secondary outcomes which will be analyzed include the time it takes to progress to dialysis, the time to reach a fifty percent reduction in kidney function, and the numbers of deaths in each group.