PURPOSE/OBJECTIVES: To examine correlates of participation in regular physical activities among young adult survivors of childhood cancers. DESIGN: Descriptive, correlational. SETTING: Web-based survey. SAMPLE: 117 well-educated, predominately Caucasian survivors of various types of childhood cancers (-X age = 24 years). METHODS: Participants completed four rating scales, a stages of change measure, and background questions. Logistic regression and graphical methods were used to examine relationships among physical activity correlates and physical activity. MAIN RESEARCH VARIABLES: Physical activity stages of change, autonomous motivation, physical activity pros and cons, self-efficacy, and self-reported worries. FINDINGS: More than 80% of participants reported that they were physically active. Survivors who were autonomously motivated and who perceived fewer cons to being physically active were more likely to report being active than survivors with lower autonomous motivation scores and higher physical activity cons scores. Worries about the present and future moderated the effect of physical activity cons on physical activity. The estimated probabilities of reporting being active for women and men changed as the collective contribution of autonomous motivation, physical activity cons, and worries varied from low to high values. CONCLUSIONS: Engaging in physical activity willingly and without a sense of pressure (autonomous motivation), perceiving fewer cons to physical activity participation (cognitive appraisal), and worrying about the present and future (affective response) were important correlates of self-reported physical activity beyond the influence of gender. IMPLICATIONS FOR NURSING: Interventions that promote autonomous motivation, decrease physical activity cons, and address present and future worries may increase physical activity in young adult cancer survivors and may have a greater impact on women than men.