Dr. Isaac Franck, 76, who turned the Jewish Community Council of Greater Washington into an influential forum on local, national and international questions during the 25 years that he served as its executive vice president, died May 14 at Georgetown University Hospital. He had cancer.

Dr. Franck took over as executive vice president of the council in 1948. The council was less than than 10 years old, having been founded only in 1939, and it had had only 57 member organizations. But 1948 was also the year the State of Israel came into being in a bloody conflict. And it was only three years after the end of the world conflict that included the Holocaust.

It was a time when the Jewish community in this area began to take on a sharper identity. Issues on which the Jewish community enjoyed general agreement were support of Israel in the international arena and support of the civil rights movement in national and local affairs.

When Dr. Franck stepped down in October, 1973, the Jewish Community Council had 173 member organizations, religious as well as secular. Israel was fighting for its existence in the Yom Kippur War.

During his tenure, Dr. Franck came as close as anyone to being a spokesman for the Jewish community here. He gave it not only a degree of cohesion, he also sought for it a special place because of its location in the nation's capital.

If the interests of Israel were Dr. Franck's top priority, he also had a profound sympathy for the plight of Soviet Jews -- he was a Russian Jew by birth. He differed with some of his colleagues about how the situation of Jews in the Soviet Union could be improved, and he was critical of the Jackson Amendment of 1972, which invoked economic sanctions against Moscow unless it allowed free emigration of its Jewish citizens.

During the 1950s, Dr. Franck's organization joined as plaintiffs in many civil rights cases. In the 1960s, Dr. Franck helped develop Washington's Urban Coalition, an alliance of business, religious and labor leaders. In 1968, when riots broke out in Washington after the assassination of Dr. Martin Luther King Jr., the coalition was called up to help dispense food, jobs and housing to hundreds of displaced families.

A measure of Dr. Franck's influence is the guest list at a luncheon given for him when he retired. Those present included Walter E. Washington, then mayor of Washington, Cardinal Patrick O'Boyle, the retired Catholic archbishhop of Washington, Rabbi Stanley Rabinowitz of the Adas Israel Congregation where Dr. Franck was a member, and Bishop John Wesley Lord, retired bishop of the United Methodist Church of Washington.

Dr. Franck came to the United States from Russia in 1923 and settled in New York City. He graduated from New York University. He was executive director of the Jewish Community Councils in Brooklyn, N.Y., and Detroit before heading the Washington organization. After moving here, he took a doctorate in sociology and philosophy at the University of Maryland. In addition to English, he was fluent in Hebrew, Yiddish, German, Russian and French.

After retiring from the community council here, Dr. Franck taught philosophy at Howard, Catholic and American universities. In 1978 and 1979, he was the Hymen Goldman Distinguished Lecturer in Jewish studies at Georgetown University. Since 1979, he had been a senior research scholar at the Kennedy Institute of Ethics at Georgetown.

Dr. Franck was a past president of the Washington Philosophy Club and had conducted seminars on psychiatry and the humanities at the Washington School of Psychiatry.

He was a member of the American Philosophical Association, the American Sociological Society, the Association for Jewish Studies, and the National Association for Social Workers.

Survivors include his wife, Pearl, and two children, Walter Franck and Phyllis Franck Tauber, all of Washington.