The notion of social capital refers to social connections between people, such as networking, trust, norms, etc. Rich and good-condition social capital is supposed to enhance collective action in a society. This is why social capital has attracted more attention in the field of development studies and environmental management studies in recent years. However, the forms and conditions of social capital are different in each society and there is no ideal social capital. Therefore, it is important to know the advantages and disadvantages of the original social capital and how it can be supplemented. In the environmental learning project in Danang, Central Vietnam, social capital was fostered through the activities of the residents' group. New and strong networks of people have been created among broader neighborhoods. The residents' group created multi- dimensional networks (bridges) in the society and helped to foster social capital. Eventually, the residents' group is expected to bring success to the participatory urban environmental project by fostering social capital in the local society.