Objective: To test the hypothesis that social marketing improves women's awareness and consumption of multivitamin and mineral supplements. Design: Formative research and baseline and final surveys using a multistaged stratified cluster sample. Setting: Department of Santa Cruz, Bolivia. Participants: Women 15 to 49 years old (n = 1709 at base-line and n = 1735 at final survey). Intervention: Social marketing campaign using radio and television spots. Main Outcome Measures: Awareness and use of multivitamins, including VitalDía, the brand promoted as part of this social marketing campaign. Analysis: Cross-tabulations to assess changes over time in awareness and use of multivitamins. Logistic regression analyses to identify determinants of multivitamin use. Results: The campaign increased women's awareness and use of multiple supplements, including VitalDía. Awareness of multiple supplements nearly doubled among women with 6 to 8 years of schooling, tripled among women with 4 to 5 years of education, and more than quadrupled among women with less than 4 years of schooling. After 9 months of social marketing, 11% of women had taken VitalDía one or more times, 7% had taken it at least once in the last 3 months, and 4% had used it one or more times in the last month. Improvements in the use of VitalDía were evident for women of all socioeconomic and educational levels, with the greatest increases occurring in the least advantaged groups. Additionally, women who had a positive perception of the benefits of multivitamins were 1.7 times (95% confidence interval 1.2-2.3; P < .01) more likely than women who did not have a positive perception to ever use VitalDía, once the effects of social class were adjusted. Conclusions and Implications: Social marketing of multiple supplements reached resource-poor women and can be used to bridge gaps in access, improve awareness of supplementation as an option, and increase the likelihood that women will try supplements.