Background. Previous stage of change research examining health behaviors has tended to examine one behavior at a time. However, one recent study by King et al. (1996) examined the relationship between smoking and exercise across cognitive-behavioral mediators (i.e., decisional balance and self-efficacy) shown to be important in predicting readiness to change. In this study, we seek to replicate the study of King et al. (1996) in a low-income sample, the majority of whom are women, with at least one chronic illness who are attending primary care clinics. Methods. Data were obtained from 270 adult outpatients attending four public primary care clinics in Louisiana. Results. Smoking and exercise stage of change were not related. Significant relationships existed between the cognitive variables of smoking and exercise. No significant differences existed within exercise stage of change on the cognitive variables of smoking, and vice versa, no significant differences were noted within smoking stage of change on the cognitive variables of exercise. Conclusions. Smoking and exercise appear to be specific health behaviors that are independent constructs in this particular sample. However, caution should be taken when interpreting the findings since 75% of the sample had at least one chronic illness. © 2003 American Health Foundation and Elsevier Science (USA). All rights reserved.