A. Michael Spence, chairman of the Economics Department, will step into big shoes when he assumes the deanship of the Faculty of Arts and Sciences at the end of the academic year.

Spence's predecessors in what is widely considered the second most powerful administrative position at Harvard include some of the most illustrious names in academia. Two recent deans went on to high government service.

But this shouldn't be surprising, given the large responsibility of the dean's job, which has grown in the post-war period to carry the duties and prestige of the presidency of many other schools.

The dean of the Faculty heads the largest of Harvard's faculties, equal in resources to the rest of the University's eight faculties combined. The dean oversees the work of some 6500 undergraduates and 2000 graduate students, close to 800 tenured and non-tenured professors, and scores of laboratories, museums and research institutions.

As head of this structure, the dean shapes policy on issues like the budget, curriculum, and tenure, and plays an influential role in the academic issues of the day.

During the 1950s, McGeorge Bundy assumed the deanship at the age of 34, making him the youngest dean ever. He supervised the expansion of Harvard into a major research university, in response to the nation's growing need for professional graduates. Bundy became President John F. Kennedy'40's national security adviser, and later the head of the Ford Foundation.

In contrast, Bundy's successor, historian Franklin L. Ford, concentrated on the expansion of Harvard's undergraduate applicant pool, which reached nation wide proportions in the 1960's. His reign came to an end in the late '60s, when student turbulence swept college campuses.

Ford suffered a stroke in the aftermath of the 1969 takeover of University Hall, and left the deanship at the end of that year. His turbulent tenure was followed by the tight-fisted rule of labor economist John T. Dunlop.

Dunlop abruptly stepped down from the post after three years to join the Nixon Administration in 1973, eventually becoming Secretary of Labor. He was replaced by another economist, Henry Rosovsky, a specialist on Japan.

Rosovsky's tenure has been marked by general peace on the Faculty and a concentration on undergraduate issues, especially creation of the much publicized Core Curriculum. Rosovsky reportedly turned down the presidencies of several universities-including Yale-to complete the Core in the mid-1970s.