The biopsychosocial model describes interactions between psychosocial and biological factors in the etiology and progression of disease. How an individual interprets and responds to the environment determines responses to stress, influences health behaviors, contributes to the neuroendocrine and immune response, and may ultimately affect health outcomes. Health psychology interventions are designed to modulate the stress response and improve health behaviors by teaching individuals more adaptive methods of interpreting life challenges and more effective coping responses. These interactions are discussed in the context of aging.