A dozen American journalists including Judith Nicol, Maryland editor of The Washington Post, have been selected to become Nieman fellows at Harvard Unversity.

Nicol, 35, has headed The Post's Maryland desk for a year. She was the paper's Virginia editor for three years before that.

The journalists are the 42nd class of Nieman fellows and will study in any part of the university in the 1979-80 academic year. The fellowships were established in memory of Lucius W. Nieman, founder of the Milwaukee Journal.

Other chosen for the program were: James Boyd, 33, editorial page editor of the Idaho Statesman, Boise; two-time Pulitzer Prize winner Stanley J. Forman, 34, a photographer for the Boston Herald American; William R. Grant, 36, education writer with the Detroit Free Press.

Also, Michael J. Kirk, 32, manager for public affairs, KCTS-TV, Seattle; Jonathan Z. Larsen, 39, former editor of the now defunct New Times Magazine, New York; Paul Lieberman, 30, an investigative reporter with the Atlanta Constitution; Lynda M. McDonnell, 29, business and labor reporter with the Minneapolis Tribune.

Also, Acel Moore, 39, reported with the Philadelphia Inquirer; Judith M. Stoia, 33, editor of the "The O'Clock News" for WGBH-TV, Boston; Jan C. Stucker, 34, special assignment writer with the Record, Columbia, S.C., and Robert R. Timberg, 39, reporter with the Baltimore Sun.