OBJECTIVES: To describe cancer caregivers' participation in health-promoting behaviors and to identify factors influencing participation. SAMPLE & SETTING: 129 informal cancer caregivers at the National Institutes of Health Clinical Center. METHODS & VARIABLES: Cross-sectional survey methodology using Health-Promoting Lifestyle Profile-II (HPLP-II), PROMISĀ® Global Physical Health, NIH Toolbox Stress and Self-Efficacy, Caregiver Reaction Assessment, and Family Care Inventory Mutuality subscale. RESULTS: Caregivers reported the highest HPLP-II subscale scores for spirituality and interpersonal relationships and the lowest for physical activity. Caregivers who were older, with lower body mass indices, in better physical health, and with higher self-efficacy and mutuality participated in more health-promoting behaviors. Sixty percent of the caregivers reported that they exercised less since becoming a caregiver, and 47% reported that their diet was worse. IMPLICATIONS FOR NURSING: Future research is needed to examine novel interventions to increase health-promoting activities in cancer caregivers, and these interventions might be strengthened by including components that focus on increasing self-efficacy and/or improving the strength of the relationship between the caregiver and care recipient. [