Developing countries, such as Indonesia, in general, is an agricultural country. Agricultural development is a prerequisite for economic growth and national development. In addition, the agricultural sector can also absorb a lot of manpower and opening of the employment, as well as foreign exchange saver. The purpose of this review is to determine the role of social capital in maintaining the optimization of local agricultural institutions in the province of Bali. Social capital consists of three main elements, namely trust, norms, and networks. Subak is an agency in Bali that handle agricultural irrigation systems. To increase the capacity of farmers and the level of adoption of agricultural innovations is needed revitalization of social capital, especially in the development and strengthening of social capital and institutional farmer. A high social capital would open the possibility of resolving the complexity of the problems more easily, so that the social capital could encourage the emergence of institutions and modern organizations with the principles of openness, and networks based on the norms and trust to achieve common goals.