About 250 people gathered in the Renwick Gallery yesterday afternoon to attend a spirited demonstration of traditional African celebrations of the first fruits of harvest, which American blacks have developed into "Kwanzaa", a holiday period to honor family and community strength and African heritage.

In the Gallery's Grand Salon, surrounded by dozens of oil paintings depicting white American life in the mid-1800s, dashiki-clad Americans sang songs in Swahili, watched a color slide show of the African celebration, and then marked the first day of Kwanzaa by singing and talking of unity.

Many blacks, like Lateesa Agunbiade, who works as a paralegal for an attorney, said that Kwanzaa is a means of reaching back across the Atlantic ocean and rekindling the embers of their African heritage.

"We came to America as slaves. We didn't come on the Mayflower. There were so many things that were lost in terms of tradition," said Agunbiade, a native of Detroit who now lives in Washington, is married to a Nigerian, and attended yesterday's celebration with her son Ade, 6 and daughter Bisi, 2.

"To me, Kwanzaa means a way of life," said Kofi Brown. "I've had it throughout my life, because my father tries to practice what he preaches."

Brown's father, Nana Kwabena (William) Brown, chief priest of the District's Temple of Nyame, a religion steeped in black liberation, preached Kwanzaa yesterday as the main speaker at a lecture-performance, held in conjunction with a Smithsonian Institution art exhibit titled, "Celebration: A World of Art and Ritual."

"Kwanzaa is a means by which those who practice it . . . can feel regenerated, get a sense of rebirth, a sense of unity, a sense of our heritage, a sense of purpose and a sense of identity," Brown said.

Kwanzaa, a week-long festivity celebrated with song, drink, fruit and kinship, was founded in 1966 by black nationalist Maulana Ron Karenga, of Parsonsburg, Md., who said that the goal of the celebration was to construct a national cultural network among black Americans, Brown said.

The seven principles of Kwanzaa are: Umoja, Swahili for unity; Kujichagulia, self-determination; Ujima, collective work and responsibility; Ujamaa, cooperative economics; Nia, purpose; Kuumba, creativity; and Imani, faith.

Officials and participants at yesterday's event said there is no accurate figure on the number of Americans who celebrate Kwanzaa, but that the festival has become signficant to a substantial segment of Washington's 70 percent-black population. They said that while most of the celebrating is done in the home, other public events are scheduled through this week.