Because irrigated land is usually more productive than rain fed land, and since in India irrigated agriculture traditionally has been taxable at higher rates, there was an incentive for rulers of the past, and their agents or feudatories, to organize and oversee the building and operation of tanks. Today as well, nations in South Asia and in many other parts of the developing world are investing in the creation and improvement of irrigation facilities, including tank irrigation. Tanks present special problems and special possibilities, and seem to be particularly complex in terms of human organization. It is the purpose of this paper to attempt to reach hypotheses regarding main elements in the organization of tank irrigation.