We describe 2 frameworks in which personality dimensions relevant to health, such as Conscientiousness, can be used to inform interventions designed to promote health aging. First, contemporary data and theory do not suggest that personality is "immutable," but instead focus on questions of who changes, in what way, why, when, and how. In fact, the notion that personality could be changed was part and parcel of many schools of psychotherapy, which suggested that long-term and meaningful change in symptoms could not be achieved without change in relevant aspects of personality. We review intervention research documenting change in personality. On the basis of an integrative view of personality as a complex system, we describe a bottom-up model of change in which interventions to change basic personality processes eventuate in changes at the trait level. A 2nd framework leverages the descriptive and predictive power of personality to tailor individual risk prediction and treatment, as well as refine public health programs, to the relevant dispositional characteristics of the target population. These methods dovetail with, and add a systematic and rigorous psychosocial dimension to, the personalized medicine and patient-centeredness movements in medicine. In addition to improving health through earlier intervention and increased fit between treatments and persons, cost-effectiveness improvements can be realized by more accurate resource allocation. Numerous examples from the personality, health, and aging literature on Conscientiousness and other traits are provided throughout, and we conclude with a series of recommendations for research in these emerging areas.