Seven hundred delegates from colleges across the nation arrived Thursday night for the annual collegiate Model U.N., sponsored by the International Relations Council, which will run through the weekend.

Graham T. Allison '62, dean of the Kennedy School of Government, opened the weekend convention Thursday night with a speech on recent complications in American diplomacy at the Sheraton Hotel in Boston, headquarters for the convention.

The delegates met yesterday in the Yard in committees patterned after actual U.N. committees and in sessions of the General Assembly and Security Council, Sam N. Levin '80, Secretary-General, said yesterday.

70 Harvard delegates represent the University, acting the parts of representatives from Afghanistan, Nicaragua, Pakistan, Yemen, and Oman.

Levin said the Nicaraguan delegate appeared in the General Assembly session yesterday in full military attire, studded with medals, a sash and red beret.

The United States delegate from Amherst College, who was lugging sheaves of documents on disarmament treaties and American military policy, said many of the delegates were more prepared for the convention than he expected.

Many universities, including the University of Baltimore which won the best delegation award last year, offer special preparatory seminars beforehand and give delegates course credit for attending, he added.

John Blacken, an assistant to Andrew Young, United States Ambassador to the U.N., will give the closing speech Sunday night, Levin said.