This study examined whether the contribution of social capital to household economic outputs was greater than that of other types of capital, whether different dimensions of social capital contribute equally to household income, and whether the role of social capital varies among different categories of households. We developed a reduced-form model of the household production function, in which social capital is treated as a production factor similar to other conventional factors such as physical capital, labor, and human capital, with household income and expenditure as dependent variables. The results show that social capital has a strong and positive contribution to household income, and the positive contribution of social capital to the general (the poor) house-hold’s income is greater than that of the paper-recycling (the rich) household’s income. In contrast to other studies, the number of memberships in associations does not have an impact on household income.