In the Central Valleys of Puebla Mexico a rural microfinance scheme called "savings box" (caja de ahorros) has been established to promote sustainable development among rural small-holders. After ten years of operation of this microfinance community scheme there is little information on the differing performance of groups and factors that influence their survival in rural communities. The study was designed to elucidate how rural microfinance is related to social, human, cultural and financial capitals as indicators of survival and sustainability of the savings and loan groups. A cross-sectional study among 34 informal microfinance groups was conducted through interviews with representatives and members of these groups. Multiple ordered logistic regression was used as a statistical technique to find causal relationships between the dependent variable expressed as the success level of the saving box and the independent variables of social, human, cultural and financial capital. Social capital, measured in terms of relations of trust, reciprocity, rules and norms, and cultural capital measured as the participation of women in leadership roles in the group, were the most important factors affecting the savings box survival and performance status. On the other hand, human capital, measured as the average schooling of treasurers, along with financial capital measured as the diversity of income sources and collective ownership of physical assets of the groups did not show statistically significant effects on success or survival of the savings box groups. Public policies and institutional support addressed to improve informal microfinance services through training, technical advice, and funding is necessary, as well as a suitable legal framework that allows the practice and research for learning and improving this kind of social institution.