BACKGROUND: An assessment of self-efficacy and social capital may have the potential to detect an effect of dynamic, complex and comprehensive collective actions in community-based health promotion. In 2003, a healthy village project was launched in Santa Cruz, Bolivia with technical assistance from the Japan International Cooperation Agency (JICA). The originally developed FORSA (Fortalecimiento de Redes de Salud) model accounted for participatory processes in which people could improve their health and well-being through individual behavioral changes and family/community-driven activities. This study aimed to examine the extent of self-efficacy and social capital obtained via project activities by a cross-sectional analysis. METHODS: We randomly selected 340 subjects from the healthy village project site and 113 subjects from a control area. Both groups were interviewed using the same structured questionnaire. Self-efficacy was assessed with a General Self-Efficacy Scale (GSES), while social capital was measured as the frequency of formal group participation in community meetings during the past three months, perceived social solidarity, and general trust. RESULTS: The study results showed that the participants in the project site had higher self-efficacy and social capital compared to those in the control site. The number of times a subject participated in the health committee activities was positively associated with the self-efficacy scale. Regarding social capital, females and lower-educated people were more likely to have had more frequent participation in formal groups; males and higher-educated participants showed less formal group participation, but more generosity to contribute money for the community. The main perceived benefit of participation in formal group activities varied among individuals. CONCLUSION: The findings suggest that people in the healthy village project site have higher self-efficacy, especially those with active participation in the health committee activities. To recruit more participants in future healthy village projects, we should consider the gender and level of education, and match the perceived benefits of participants accordingly.