Washington Dossier, the magazine of the social set, has listed what it believes to be "The Social 400" in the upcoming issue. Emphasizing the importance of Washington parties, Dossier quotes historian Arthur Schlesinger Jr., who once said of Washington: "Half the essential business of government is still transacted in the evening." Among the 400, the magazine lists the obvious superstars whose presence can guarantee any party's success -- President Reagan and Nancy Reagan, Vice President George Bush and Barbara Bush, House Speaker Tip O'Neill and Mildred O'Neill, Chief Justice Warren Burger and Elvera Burger, Secretary of State George Shultz and Helena Shultz, Justice Sandra Day O'Connor and John O'Connor, Transportation Secretary Elizabeth Dole and Senate Majority Leader Robert Dole, Mayor Marion Barry and Effi Barry and Washington Post Co. Chairman Katharine Graham . . .

Gwendolyn Brooks, the Library of Congress' new poetry consultant, conducted her first reading at the library Monday to a standing-room-only audience. The Pulitzer Prize winner read to a crowd of 600, but another 450 were turned away for lack of space in the auditorium . . .

Wandering minstrel Burl Ives, who is still chasing the blue-tail fly, will be in town Sunday for a benefit performance for the Kennedy Center Education Programs in the Concert Hall. He'll also be autographing books at noon Friday at Olsson's Books and Records at Dupont Circle . . .

Divorces pending: Shipping heiress Christina Onassis has filed for divorce from her fourth husband, French businessman Thierry Roussel. The couple were married in 1984 and have an 8-month-old daughter. It is his first marriage . . . San Francisco Examiner President Randolph A. Hearst, the father of Patricia Hearst, has filed for divorce from his second wife, Maria . . .

From "Charlotte's Web" -- in memory of E.B. White: "It was the best place to be, thought Wilbur, this warm delicious cellar, with the garrulous geese, the changing seasons, the heat of the sun, the passage of swallows, the nearness of rats, the sameness of sheep, the love of spiders, the smell of manure, and the glory of everything."