Gilliam first joined The Post in 1961. She came to The Post as a general assignment reporter for the metropolitan news desk. In the mid-60's, Gilliam left The Post to have more time with her children. She was a part-time reporter for WTTG's television program, "Panorama" in Washington, D.C., and wrote free-lance magazine articles.

She returned to The Post in 1972 as assistant editor of the Style section. From 1979 until 1997 she worked as a columnist writing about life in the nation's capital.

Prior to joining The Post in 1961, she was an associate editor for Jet Magazine for two years, and then spent another two years as associate director of information for the Tuskegee Institute in Tuskegee, Alabama.

Gilliam has served as chair of the board of directors of the Institute for Journalism Education, an organization that promotes racial diversity in the media. She is past president of the National Association of Black Journalists (NABJ). In 1991 she was a fellow at the Freedom Forum Media Studies Center at Columbia University, studying racial diversity in the American media. In the fall of 1996 she was a fellow at the Institute of Politics, John F. Kennedy School of Government at Harvard University. Last summer she trained South African journalists as a Knight International Press Fellow.

Among the honors she has received are the National Association of Black Journalists Hall of Fame, University of Missouri Honor Medal in Journalism, the Columbia Graduate School of Journalism Alumni of the Year Award; the Ann O'Hare McCormick Award from the New York Newspaper Woman's Club; Journalist of the Year, Achievement in Journalism, and the Washington MediaAwards from the Capital Press Club; and the Unity Award in Journalism from Lincoln University in Missouri. She is also a member of the NABJ Hall of Fame. She is author of Paul Robeson, All American, published in 1976.

Born in Memphis, Tennessee, Gilliam was graduated laude from Lincoln University in Jefferson City, Missouri with a Bachelor of Arts in Journalism. She earned her master's degree at the Columbia University Graduate School of Journalism.