James Rodney Schlesinger was born in New York City on Feb. 15, 1929, the son of Julius and Rhea Schlesinger, immigrants from Austria and Russia respectively. He was raised in a Jewish household but became a Lutheran as an adult. He attended Horace Mann School in the Bronx and Harvard, where he earned a bachelor’s degree in 1950, a master’s in 1952 and a doctorate in 1956, all in economics.
From 1955 to 1963, Mr. Schlesinger taught economics at the University of Virginia. His 1960 book, “The Political Economy of National Security,” drew attention at the RAND Corporation, which hired him in 1963. He analyzed nuclear proliferation there and became director of strategic studies in 1967.
Mr. Schlesinger joined the Nixon administration in 1969 as assistant director of the Bureau of the Budget, and drew the president’s attention by challenging a Pentagon weapons proposal in his presence.
In 1971, Nixon named him chairman of the Atomic Energy Commission, formed after World War II to promote nuclear energy.
In February 1973, Mr. Schlesinger was named director of Central Intelligence, succeeding Richard Helms, who had been fired by Nixon for refusing to block the Watergate investigation. His five-month C.I.A. tenure was stormy. He was appalled to learn that agents prohibited from spying on Americans had carried out domestic break-ins for the White House. He purged 1,000 of 17,000 employees and ordered a sweeping investigation into past operations.
That investigation eventually turned up evidence of widespread illegality. (The findings were not made public until 2007, and then were heavily censored.) But the inquiry had barely begun when, in July 1973, Nixon chose Mr. Schlesinger for the Pentagon job, replacing Elliot Richardson, who became attorney general.
His tenure at the Pentagon was little more than two years, from 1973 to 1975, but it was a time of turmoil and transition. In the days leading up to Nixon’s resignation in August 1974, Mr. Schlesinger, as he confirmed years later, became so worried that Nixon was unstable that he instructed the military not to react to White House orders, particularly on nuclear arms, unless cleared by him or Secretary of State Henry A. Kissinger. He also drew up plans to deploy troops in Washington in the event of any problems with a peaceful presidential succession.
In recent years, in addition to being a trustee of the Center for Strategic and International Studies, Mr. Schlesinger was chairman of the Mitre Corporation. He wrote no autobiography, but synthesized much of his experience in a 1989 book, “America at Century’s End.”
In 1954 he married Rachel Mellinger, a Radcliffe student. Mrs. Schlesinger died in 1995. Mr. Schlesinger is survived by his sons Charles, William, Thomas and James Jr.; his daughters, Cora, Ann, Emily and Clara; and 11 grandchildren.