Interventions encouraging adoption of healthy diets and increased physical activity are needed to achieve national goals for preventing and treating hypertension, cardiovascular disease, diabetes, and other chronic diseases. PREMIER was a multicenter clinical trial testing the effects of two lifestyle interventions on blood pressure control, compared with advice only. Both interventions implemented established national guidelines for blood pressure control (weight loss, reduced sodium and alcohol intake, and increased physical activity), and one intervention also included the Dietary Approaches to Stop Hypertension (DASH) diet. Both interventions focused on behavioral self-management, motivational enhancement, and personalized feedback. This article describes the design and evaluation approaches for these interventions. Evaluation of multicomponent lifestyle change interventions can help us understand the benefits and difficulties of making multiple lifestyle changes concurrently and the effects such changes can have on blood pressure, particularly in minorities at higher risk for hypertension.