Donald T. Regan, 61, is chairman of Merrill Lynch & Co., the nation's largest brokerage house. He is a Cambridge, Mass., native and a Harvard graduate. Regan, a former vice chairman and director of the New York Exchange, is a member of the Business Roundtable and Council on Foreign Relations. Defense

Caspar Weinberger, 63, is vice president of the Bechtel Group, an international construction and engineering firm. The Californian served as Reagan's California state finance director before serving as Richard Nixon's Federal Trade Commission chairman, budget director and secretary of health, education and welfare. Attorney General

William French Smith, 63, was Reagan's personal attorney, a senior partner in Los Angeles firm of Gibson, Dunn and Crutcher and a "kitchen cabinet" member. Smith is a native of New Hampshire, has a law degree from Harvard, is a director of several banks and utilities and a regent of the University of California. CIA

William J. Casey, 67, a lawyer and long-time Reagan friend, ran his campaign last fall. Casey is a Fordham graduate and was London headquarters chief of the Office of Strategic Services in World War II. He served as undersecretary of state and chairman of the Securities and Exchange Commission under Nixon. Health and Human Services

Richard Schweiker, 54, served Pennsylvania in both the House and Senate during 20 years in Washington. He was designated as Reagan's running mate in 1976, before Ford got the nomination. Commerce

Malcolm Baldrige, 58, was chairman and chief executive officer of Scovill Inc., of Waterbury, Conn. He is an avid rodeo participant and a graduate of Yale. He serves on the boards and was chairman of the Connecticut "Bush for President " committee in 1980. Transportation

Drew Lewis, 49, was an unsuccessful candidate for governor of Pennsylvania in 1974. He was a Republican national committeeman, a deputy chairman of the Republican National Committee and deputy chairman of the Reagan compaign. Education

Terrel H. Bell, 59, Utah commissioner of higher education and chief executive officer of the Utah State Board of Regents, is an Idaho native. He received his doctorate in educational administration from the University of Utah and served as U.S. commissioner of education in the Nixon and Ford administrations. Budget

David A. Stockman, 34, a Michigan congressman first elected in 1976, did graduate work at the Harvard Divinity School and was a Harvard Institute of Politics fellow. Agriculture

John R. Block, 45, was Illinois agriculture secretary when Reagan selected him for the Cabinet. He owns a 3,000-acre family farm near Galesburg, Ill., where he raises hogs, corn and soybeans. Block is a graduate of West Point and has served on numerous boards concerned with farm exports. State

Alexander Haig, 56, was president and chief operating officer of United Technologies Corp. in Hartford, Conn. He is a former NATO commander and was chief of staff to Nixon in the last days of that administration. Haig grew up in a wealthy Philadelphia suburb and made a career of the military. Labor

Raymond Donovan, 50, was executive vice president of Schiavone Construction in Secaucus, N.J. He was Reagan's New Jersey campaign manager. Housing

Samuel R. Pierce, 58, was a senior partner in the New York law firm of Battle, Fowler, Jaffin, Pierce and Kheel and a former New York Supreme Court justice. He held posts in the Treasury and Labor departments under Nixon. Interior

James G. Watt, 42, was president and chief legal officer of the Mountain States Legal Foundation. He is a Wyoming native and served as a consultant to Walter Hickel, then interior secretary, in 1969. He is a former director of the Bureau of Outdoor Recreation and Federal Power Commission member. Energy

James B. Edwards, 53, a graduate of the University of Louisville School of Dentistry, was an oral surgeon in Charleston, S.C. He served as governor of South Carolina from 1975 to 1978 and as chairman of the Southern Governors Conference in 1978. He's been active in Republican politics since 1964. United Nations

Jeane J. Kirkpatrick, 54, was a Georgetown University professor of political science. She is a Democrat, but also is a member of the American Enterprise Institute, a conservative-oriented think tank. Kirkpatrick has written three books and is considered an authority on Latin America. Trade

Bill Brock, 50, a native of Tennessee, was an executive of the Brock Candy Co., a family business. He was chairman of the Republican National Committee in 1980, and served as a U.S. representative from Tennessee for four terms and as a U.S. senator for one term. Economic Advisers Council

Murray Weidenbaum, 53, was on the faculty of Washington University in St. Louis, where he was associated with the Center for the Study of American Business. He served as an assistant treasury secretary in the Nixon administration and has written extensively on federal economics. Counselor

Edwin Meese III, 48, a San Diego lawyer, was Reagan's executive secretary when he was governor of California. He took a leave from San Diego University to be 1980 campaign chief of staff. Chief of Staff

James A. Baker, III, 51, a lawyer, directed President Ford's 1976 campaign and George Bush's 1980 presidential campaign before coming to the Reagan staff. He was undersecretary of commerce in the Ford administration. Deputy Staff Chief

Michael K. Deaver, 42, a Los Angeles publicist, has been a close adviser since Reagan was California governor. A veteran of the 1976 presidential campaign, Deaver left the 1980 campaign briefly, rejoining it after campaign manager John Sears left. Press Secretary

James Brady, 40, is a veteran Washington press secretary, having served at the Department of Housing and Urban Development, the Office of Management and Budget and the Department of Defense. He is a former press aide to Sen. William Roth (R-Del.). Domestic Affairs

Martin Anderson, 44, an economist, was a deputy counselor in the Nixon White House, leaving in 1971 to become a senior fellow at the conservative Hoover Institution. In 1976 and 1980, he was Reagan's chief issues adviser. National Security

Richard V. Allen, 45, was an aide to former secretary of state Henry A. Kissinger and later was a deputy assistant to President Nixon. Allen is a co-founder of the Georgetown University Center for Strategic and International Studies. Political

Lyn Nofziger, 56, an ex-political reporter, was public relations director of Reagan's first campaign in 1966, and a key political adviser during his early years as governor. He managed Nixon's California campaign in 1972, rejoining Reagan in 1976. Pollster

Richard Wirthlin, 49, a former economics professor, emerged as one of the strategic heroes of the 1980 campaign when Reagan took his advice to make an effort among blue-collar workers. Congressional Liaison

Max Friedersdorf, 51, gave up the chairmanship of the Federal Election Commission to join Reagan's White House staff. He was staff director for the U.S. Senate Republican Policy Committee. Public Liaison

Elizabeth Dole, 44, is a former Federal Trade Commissioner. She started her career at the Department of Health, Education and Welfare.