Toting sleeping bags, colorful posters and electric guitars, about 50 students last night launched today's national anti-apartheid protest by setting up camp on the lawn outside President Derek C. Bok's Massachusetts Hall office.

Harvard's contribution to the United Nations-declared "National Anti-Apartheid Day" will culminate outside Lamont Library at noon today, with a rally outside featuring former Boston Mayoral candidate Melvin H. King.

This evening students also plan to hold a mock funeral procession and candlelight vigil at Memorial Church to commemorate Blacks who have died in South Africa.

Last night's sleep-in, which was organized by a Law School anti-apartheid group, ends today at 9 a.m. with a demonstration and open discussion about apartheid. The protesters spent yesterday afternoon and last night reading poetry, singing folk songs and listening to a handful of speakers while sprawled on sidewalks chalked with "You Pay For Apartheid Slavery."

By late last night about 150 passersby had signed a letter to South African Bishop Desmond M. Tutu denouncing the Reverend Jerry Falwell's stated support a month ago of the South African government.

Harvard Vice President and General Counsel Daniel Steiner '54 signed the letter when he emerged from his office at 7 p.m. He said later that he had done so not as a member of the University, but as an individual.

Organizers described yesterday's turnout as disappointing, attributing it to the beginning of the Law School summer job interview season. "Once you get into a professional school, you have less time to commit to an outside rally," said second-year student Timothy Galloway.

Harvard police officials said they don't anticipate any problems with security at today's rally and won't be taking any special precautions.

The Kuumba Singers, a black choral group, will open and close the event. In addition to King, featured speakers will include Stanley Hoff- man, Dillon Professor of the Civilization of France.

Representatives from the African National Congress--the banned Black South African protest group--as well as students activists from Harvard and other schools are expected to speak at the event, which is sponsored by Southern African Solidarity Committee and the Third World Students Alliance.

Later today a group of Harvard students is planning to join a number of Boston-area schools in picketing IBM's South Africa-related operations outside its Copley Square office