Alcohol consumption has been recognized as an important correlate of blood pressure in many epidemiologic studies, but few interventional studies have been conducted to examine the effect of a reduction in alcohol intake on blood pressure. Because these studies have usually included few subjects and been of short duration, the National Heart, Lung, and Blood Institute (NHLBI), the National Institute on Alcohol Abuse and Alcoholism (NIAAA), and the Veterans Affairs (VA) Cooperative Studies Program have initiated a randomized, controlled, multicenter trial to determine whether blood pressure and left ventricular mass are lowered over 6 months of alcohol moderation in non-dependent moderate to heavy drinkers (three or more drinks per day average but not alcohol dependent) with above-average normal (80 to 89 mm Hg) and mildly hypertensive (90 to 99 mm Hg) levels of diastolic blood pressure, and whether a reduction in alcohol intake can be maintained for 2 years. Eligible veterans are randomized to either an alcohol reduction intervention or a control observation group at seven clinical sites. The projected sample size is 580 participants. Alcohol intake is assessed by self-report using a retrospective diary (Chronological Drinking Record) and by various biochemical markers, including apolipoproteins, HDL cholesterol (and subfractions), and carbohydrate deficient transferrin, analyzed at a central laboratory. The alcohol intervention technique is a cognitive-behavioral program, the intensive phase of which consists of six counseling sessions over 3 months. Echocardiograms are obtained at baseline and 6 months after randomization. This trial has important implications for both the prevention and treatment of hypertension.