Hypertension, or high blood pressure, involves multiple physiological, psychosocial, behavioral, dietary, and other factors in its etiology and treatment. The disorder fits well into the biobehavioral framework of behavioral medicine. Among the variables that influence blood pressure and hypertension are the following; family history, personality, stress (natural disasters, culture and urbanization, occupational stress, prolonged illness, experimentally-induced stress, response to stress in individuals with a family history of hypertension, Type A behavior), and other factors (obesity, physical activity, dietary sodium, caffeine and alcohol). Evidence concerning these factors and their interaction is presented, and suggestions are made for further research. The major nonpharmacologic approaches to treatment of hypertension include modification of physical risk factors (sodium restriction, weight loss, reduced caffeine and alcohol, physical training, drug adherence) and behavioral treatment methods (direct regulation of blood pressure using biofeedback, regulation of sympathetic nervous activity, relaxation, stress management). These methods are appraised and suggestions are offered on improving the quality of treatment research in selection of patients and initial assessments, blood pressure assessment, maintenance and follow-up, generalization of treatment effects, and other areas.