Harvard junior Alexander Bok won a place on the Massachusetts delegate slate of Sen. Edward M. Kennedy '54 (D-Mass) in balloting yesterday.

Bok, who finished fifth in a field of 16, will fo to the national convention pledged to Kennedy if Kennedy wins over two-thirds of the vote in the Eighth District; which includes Cambridge.

Ahead of Bok as Kennedy delegates are Cambridge Kennedy organize James Roosevelt and Somerville Alderman Sal Albano, Cambridge school committee vice chairman Alice Wolf and National Organization for Women activist Mary Trowbridge. Boston resident Margaret Williams is the sixth district Kennedy delegate.

Biggest Turnout

More than 650 people turned out for yesterday;s Kennedy caucus, held in East Cambridge's Kennedy public school. The Carter caucus held in East Boston drew only 150, and 35 supporters of California Gov. Edmund G. Brown Jr. gathered in Cambridge's Tobin School, organizers of those meetings said.

Because he was the fifth delegates selected, Bok said after the caucus chances were slim he would win a convention seat in the primary balloting March 4.

He added, however, that his strong showing in the crowded caucus might convince the Democratic State Committee to name him to one of the delegate slots reserved for students under its affirmative action program.

Bok, a second cousin of President Bok, credited the support of local political figures, including state senate candidate Jarvis Kellogg, and "convincing literature," as reasons for his upset victory.

"Also, a lot of people told me they thought one out of the six ought to be a student," Bok said. "I guarantee you not more than 25 people knew my name when I walked in here," Bok, who drew more than 170 votes on the first ballot, added.