BACKGROUND: There is an established link between socioeconomic status (SES) and performance of health behaviors with more health protective and fewer health-risking behaviors in higher SES groups. PURPOSE: This research is novel in testing the moderating effect of SES on the relationship among intention, self-efficacy, and subsequent behavior. METHODS: Effects were tested on data from three prospective correlational studies examining smoking initiation in adolescents (N = 826), breastfeeding in primiparous women (N = 202), and physical activity in working adults (N = 509). RESULTS: Despite examining different behaviors, samples, time intervals, and measures of SES, each study showed significant interactions between intention and SES in predicting behavior. In all three tests, the intention-behavior relationship was attenuated among individuals from lower SES groups. No moderation effects of SES were found for self-efficacy. CONCLUSIONS: The intention-health behavior relationship can be attenuated in lower SES samples. This finding may contribute to our understanding of SES differences in health behaviors.