This chapter addresses the importance of dispositional optimism for subjective well-being and physical health. Based on theories of self-regulation, we discuss how generalized optimistic, as compared to pessimistic, expectations about future outcomes can foster the pursuit of valued goals, help people adjust to stress and goal constraints, and contribute to their well-being and health. In addition, literature is reviewed supporting the adaptive value of dispositional optimism for subjective well-being and physical health. This literature further points to the importance of coping and social resources in these associations. Finally, several issues are raised that may further our understanding of the roles of optimism in influencing a person’s quality of life. These issues include developmental aspects of dispositional optimism, and a conceptual and empirical consideration of whether the presence of optimism can confer different benefits for well-being and health than the absence of pessimism.