The first citizens of cities ranging from Boise, Idaho and Austin, Texas to New Bedford, Mass. and Sunnyvale, Cal. checked into town yesterday for a five-day conference for newly-elected mayors at the Kennedy School.

During their time here the mayors will be wined, dined and lectured by a faculty culled from Kennedy School professors, political consultants, Massachusetts bureaucrats and fellow politicians, including Gov. Michael S. Dukakis and San Antonio Mayor Henry Cisneros. The bienniel program, which began in 1975, is sponsored by Harvard's Institute of Politics and the U.S. Conference of Mayors.

"We are helping these mayors with the transition period" into office, Charles Trueheart, director of the Institute of Politics Forum, said. "The mayors are exposed to a quick overview and to the best thinking on issues which will confront them."

After registering last night at the Charles Hotel, the mayors gathered at the Kennedy School for cocktails and dinner, before listening to Cisneros speak on "The Experience of Being Mayor."

The rest of the seminar is packed with courses on issues and problems which will confront these mayors during their terms in office.

The first day of the seminar will address the problems of transition and how to run a mayor's office. The second day will examine government management and finances. The last two days will examine specific issues which politicians must handle, such as press relations, labor relations, and crime fighting.

Most of the conference is closed to the press and public, and a number of mayors interviewed yesterday as they walked to the cocktail party had little to say about the affair.

The mayors won't just be hitting the books; they'll be shaking hands, meeting colleagues and greeting the likes of President Derek C. Bok. Part of the conference experience is designed to help the mayors "network," Trueheart said.

Any mayor newly-elected to a city of more than 100,000 people is invited to come to the conference, Trueheart said. About two-thirds of those invited attend, he added.