Invitations--6400 of them--went out this week inviting the entire Harvard undergraduate body to the Student Assembly's Boston-Boston gala, set for Sunday night at the city's largest discotheque.

"It's a private party at Boston-Boston," Sarah V. Carpenter '81, chairman of the social committee sponsoring the event, said yesterday. "We don't expect everyone to show up, but it's a great way to celebrate the new semester," she added.

No Student Assembly funds have been spent on the party. "Boston-Boston is paying for everything, from the invitations to the transportation," Carpenter said. The disco will provide free transportation on buses it has rented. The buses will run about every 20 minutes from Harvard Square and the Quad to 15 Landowne Street and back again. The buses will keep running until 2:30 a.m., so people won't be forced to leave early to catch a subway home.

Patrick T. Lyons, general manager of Boston-Boston, said yesterday that they expect about 1700 people to show up Sunday night; and he said if everything works out he'd like to make the party an annual event.

"Harvard people are desirable people--they are a pleasant, well-behaved, clean crowd. We'd do this monthly if we could," Lyons said.

"We wanted to do something fun and not have to worry about the politics for a change," John C. Ramig '80, a member of