Politically active actress Jane Fonda will be in town next Friday for the Washington opening of her new movie, "Agnes of God," which also stars Anne Bancroft and Meg Tilly. She will be here with the film's producer-director Norman Jewison for the Democratic Congressional Campaign Committee's fundraiser showing of the film and a buffet dinner afterward at the Women's National Democratic Club. The film opens here on Sept. 27 . . .

Rep. Claude Pepper, the oldest member of Congress, celebrated his 85th birthday yesterday at a champagne-and-cake reception that also saluted the 50th anniversary of Social Security. House Speaker Tip O'Neill was to crown Pepper the "King of Social Security," and some of his other colleagues -- including former senator Jennings Randolph, House Majority Leader Jim Wright and Rep. Mary Rose Oakar -- were scheduled to speak . Pepper's birthday was Sunday . . .

Rep. Joseph P. Addabbo is listed in stable condition at Walter Reed Army Medical Center. The 60-year-old New York Democrat was hospitalized late last month and surgery was performed for malfunctioning kidneys. He is expected to be back to work in another month . . .

It's beginning to look as though Bantam Books knew what it was doing in paying $1 million for Geraldine Ferraro's upcoming book "Ferraro: My Story." The Book-of-the-Month Club has designated the book, cowritten by Linda Bird Francke, as one of its main selections for January. Because of the interest, 200,000 copies of the former congresswoman's story about her run for the vice presidency are being printed for shipment next month . . .

Fashion designer Laura Ashley is in critical condition in a hospital in the English Midlands after suffering head injuries in a fall down a flight of stairs. She is 60 years old.