(FORTUNE Magazine) – More women are moving into the boardrooms of the top U.S. corporations, according to a survey by executive recruiter Korn/Ferry International. Lois Dickson Rice, 56, a senior vice president of Control Data, was elected last June to the board of McGraw-Hill, where she is the only female. Others include Elizabeth E. Bailey, 50, dean of Carnegie Mellon's business school, who joined three other women on Philip Morris's 22-member board in January, and Mildred S. Dresselhaus, 58, an MIT physicist who became Quantum Chemical's first female board member last April. The advance of women as directors outpaces that of black males. Their share of directorships is up by an estimated 23% since 1983, vs. 58% for females.