This chapter outlines the primary psychological and social factors that influence the development and maintenance of several physical disorders. Specifically, the psychological effects of stress on the immune system and related diseases are described. Emphasis is given to AIDS, cancer, cardiovascular disease, hypertension, coronary heart disease, chronic pain, and chronic fatigue syndrome. In addition, lifestyle practices that place one at risk for certain physical disorders are discussed. Finally, both limited and comprehensive psychosocial treatment and prevention efforts for these problems are delineated.Learning ObjectivesLEARNING OBJECTIVESDistinguish between behavioral medicine and health psychology.Identify the relationships among immune system function, stress, and physical disorders.Describe the relationships among stress and cardiovascular disease, AIDS,and cancer.Define acute and chronic pain and identify their potential causes.Identify some procedures and strategies used in stress management, and prevention and intervention programs.