The public is increasingly going to Wikipedia as a research source: According to a recent Pew survey, the percentage of all American adults who use the site to look for information increased to 42 percent in May 2010, from 25 percent in February 2007. This translates to 53 percent of adults who regularly use the Internet.

Jane Margolis, co-author of a book on sexism in computer science, “Unlocking the Clubhouse,” argues that Wikipedia is experiencing the same problems of the offline world, where women are less willing to assert their opinions in public. “In almost every space, who are the authorities, the politicians, writers for op-ed pages?” said Ms. Margolis, a senior researcher at the Institute for Democracy, Education and Access at the University of California, Los Angeles.

According to the OpEd Project, an organization based in New York that monitors the gender breakdown of contributors to “public thought-leadership forums,” a participation rate of roughly 85-to-15 percent, men to women, is common  whether members of Congress, or writers on The New York Times and Washington Post Op-Ed pages.

It would seem to be an irony that Wikipedia, where the amateur contributor is celebrated, is experiencing the same problem as forums that require expertise. But Catherine Orenstein, the founder and director of the OpEd Project, said many women lacked the confidence to put forth their views. “When you are a minority voice, you begin to doubt your own competencies,” she said.

She said her group had persuaded women to express themselves by urging them to shift the focus “away from oneself  ‘do I know enough, am I bragging?’  and turn the focus outward, thinking about the value of your knowledge.”

Ms. Margolis said she was an advocate of recruiting women as a group to fields or forums where they are under-represented. That way, a solitary woman does not face the burden alone.

Ms. Gardner said that for now she was trying to use subtle persuasion and outreach through her foundation to welcome all newcomers to Wikipedia, rather than advocate for women-specific remedies like recruitment or quotas.