If Harvard Yard feels a bit more diplomatic this weekend, it's thanks to the 2,500 high school students from across the country and the globe, wielding briefcases stuffed with position papers and ready to tackle the world's problems.

The 42nd annual conference of Harvard Model United Nations (HMUN), a branch of the International Relations Council, began Thursday evening and will conclude Sunday afternoon. More than 150 Harvard students will also participate in the conference as officers and staff members.

Yesterday, dubbed "Harvard Day," high-schoolers toured Boston and the Harvard campus, observed large lecture classes such as Chemistry 10 and began their committee meetings in buildings across the Yard.

The remainder of the conference will be held at the Boston Sheraton hotel.

Only Georgetown University sponsors a model U.N. conference for high school students comparable in size to Harvard's said Zainab Khan '96, publicity director for HMUN.

"There are many conferences for college students, but the high-schoolers come with so much more enthusiasm," Khan said. "It's important for them to know what the U.N. can and can't do."

Harvard students are attracted to HMUN because it provides the opportunity to teach high school students about international diplomacy, a subject in which they may not have much experience, according to Jojo C. Liu '96. Liu is under-secretary-general for the conference's Economic and Social Council.

"Students see that their range of responsibili- ties extends past their schools," Liss said.

The Secretary-General this year is Joshus C. Vetney '96.

On Thursday, Frederick Price Du Val, deputy chief of protocol of the United States, gave the keynote address for the conference and stressed the importance of reaffirming support for international peace and justice.

This year, Khan said, HMUN expended its grants program and allocated nearly $2000 to enable eight students from a Boston public high school, the Muriel S. Snowden International School at Copley, to attend the conference for free.

"Schools from around the world come, but there are kids in the Boston public schools who don't get the experience," Khan said. "This is a step in the right direction, but at this point it's all we can afford."

The Snowden students appreciated the opportunity to attend, according to the team's adviser, Steven Seto.

"We bring a local urban attitude," Seto said of his group's participation. "We're here--this is home territory for us."

Before arriving in Cambridge, students are assigned to work on a particular issue from the perspective of a U.N. member state.

Each school receives "study guides" addressing the topics which committees will discuss at the conference.