OBJECTIVE: To ascertain factors related to readiness to change behavioral risk factors in members of a managed care organization (MCO). STUDY DESIGN: Cross-sectional study. PATIENTS AND METHODS: A telephone survey reached 4667 (73%) of 6409 adult members of a Minnesota MCO attending 2 primary care clinics. Of these, 3826 members (82%) completed an interview designed to identify behavioral risk factors (smoking, consuming a high-fat diet, and physical inactivity) and readiness to change these behaviors. RESULTS: Among MCO members consuming a high-fat diet, those most ready to change were older, were women, used more preventive services, and reported receiving professional advice about diet. For physical inactivity, those most ready to change were younger, women, and more educated; used more preventive services; and reported receiving professional advice about physical activity. Among smokers, those with higher readiness to change smoked fewer than 15 cigarettes a day, had higher self-efficacy, had no other smokers in the household, and reported receiving professional advice about smoking. After controlling for demographic variables and for use of preventive services, greater readiness to change for smoking (beta = 0.336, odds ratio [OR] = 1.40, P = .056), physical activity (beta = 0.651, OR = 1.92, P < .001), and diet (beta = 0.532, OR = 1.70, P < .001) was associated with having received professional advice to change these behaviors. CONCLUSIONS: Levels of readiness to change behaviors in MCO members who smoke, are inactive, or consume high-fat diets are similar to those reported in other populations. The association of professional advice to change behaviors with increased readiness to change for smoking, physical activity, and diet suggests that receiving professional advice on these topics might assist patients in changing adverse health-related behaviors.