William S. Gaud, a former administrator of the Agency for International Development who emphasized food production and population control, died Monday of cancer at the Washington Home for Incurables. He was 70.

Mr. Gaud coined the term "the green revolution" to dramatize his belief that the use of new, high-yield kinds of wheat and rice could help the underdeveloped world feed itself. He was equally certain that the breakthroughs in agriculture would come to nothing unless they were matched by massive efforts to control population.

Mr. Gaud joined AID when it was first set up in 1961 at the outset of the Kennedy administration. He as in charge of its operations in the Near East and South Asia until 1964, when he became deputy administrator. From 1966 to 1969, he was administrator.

The increase in food production this period - particularly in Turkey, India and Pakistan - was astonishing. In 1964, India produced 9.8 million tons of wheat. In 1969, it produced 18 million tons. Pakistan's yield rose from 4 million to 7 million tons in the same five years.

These increases were made possible by the introduction of strains of wheat developed in Mexico under the auspices of the Ford and Rockefeller foundations. The foundations also developed high-yield rice in the Philippines.

Mr. Gaud's contribution was to make them available to the countries that needed them. President Johnson had proclaimed a "war on hunger" and the foreign aid programs were the means by which it was to be fought.

President Johnson announced in 1965 that the United States would finance birth control programs abroad. This was a sharp departure from previous policies.

Mr. Gaud felt that these two efforts - food production and population control - would permit the world to feed itself and avoid massive famines. He did not think that the task would be easy.

The developing countries, he told Congress in 1968, "lack the skills to do the necessary adaptive research. They lack the foreign exchange to import fertilizer. They lack the capital to build fertilizer plants. They lack the facilities and techniques needed to train their people in the new ways."

The United States and other rich countries must fill these needs, he said.

The new grains, he wrote in a letter published in The Washington Post in 1968, would allow the world to meet its "medium term" requirements. He added, "But this is not enough for the long term. Today's rapid rate of population growth must be slowed or people will outstrip even this expanded food supply before the turn of the century.

"To meet the long-term challenge of moderating the population increase, AID gives family-planning programs the highest priority, together with assistance to agriculture."

The 1960s were what one former associate of Mr. Gaud called the "golden era" of cooperation between the United States and India and Pakistan. But foreign aid, as well as many other programs, began to run into increasing difficulties in Congress from critics of the war in Vietnam. Much of Mr. Gaud's tenure as administrator of AID was devoted to trying to preserve the programs in which he was most interested in the face of this criticism.

When he left government, Mr. Gaud became the executive vice president of the Internation Finance Corporation of the World Bank Group. He remained there until 1974, when he became a consultant to the World Bank and president of the Population Crisis Committee, a private organization that promotes population control.

Robert S. McNamara, the president of the World Bank and the former Secretary of Defense, said yesterday that Mr. Gaud was "one of the most dedicated officers I have worked with in my 17 years in government and international organizations."

Moeen A. Qureshi, Mr. Gaud's successor at the International Finance Corporation, called his death a loss "to the peoples of the developing world for whom he worked so hard and accomplished so much."

Mr. Gaud was born in New York City and earned bachelor's and law degrees at Yale University. After teaching briefly at Yale and then starting a private law practice in New York, he became an assistant corporation counsel for New York City. One of the projects on which he worked was the city's acquisition of control over its subway system.

He served in the Army in the China-Burma-India theater during World War II. There he worked with Dean Rusk, who was secretary of State in the Kennedy and Johnson administrations. It was Rusk who persuaded Mr. Gaud to give up his New York law practice after the war and come to Washington in 1961.

Mr. Gaud's survivors include his wife, the former Eleanor Mason Smith, of the home in Washington; a daughter, Anne Tinker, also of Washington, and a brother, Henry Taylor Gaud, and a sister, Mrs. John Leland, both of Charleston, S.C.