Nadia Al-Dossary knew she had arrived when she ran across a picture of herself on the internet—with a mustache drawn across her face. The image, she says, was posted by "one of those bearded bloggers," as she calls the Saudi conservatives who condemn her. "I was very happy," she says, laughing. "If the other women and I weren't making a difference, they wouldn't challenge us."

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Al-Dossary has become a pro at pushing against the boundaries of acceptable behavior for Saudi women. Not yet 40, she runs Saudi Arabia's largest scrap-metal business, $500 million-plus Al-Sale Trading and Contracting Company, and even though she didn't win the chamber of commerce seat after a campaign for it that earned her the attention of the bearded bloggers, she's leading a pack of women who are controlling more of the nation's wealth, and increasingly moving into positions of power.

Today, women constitute about 55 percent of the kingdom's college graduates. They own 10 percent of the country's real estate, one-third of the brokerage accounts, and about 40 percent of the country's family-run companies (albeit mostly as silent partners), according to a recent report from the Economist Intelligence Unit. The E.I.U. further estimates that Saudi women have about $12 billion in cash, with three-quarters of it sitting in banks, much of it from inheritances.

In addition to Al-Dossary, these women include Nahed Taher, who went to Bahrain to set up her own investment bank in 2005 and has since become a major investor in infrastructure and energy projects in the region; Nabilah Tunisi, a leading executive at Saudi oil giant Aramco, who oversees 380 engineers as a manager on project support and controls; and Samra Al-Kuwaiz, the managing director of the women's division of Osool Brokerage Company, which is tapping into the growing wealth of the country's women.

Saudi Arabia is decidedly not an easy place for women to succeed: Women are not permitted to drive or vote, and until January, could only travel if accompanied by a mahram, or male guardian. Men and women who are not related to each other are not allowed to appear together in public (which makes business meetings difficult), and a woman who wants to operate any venture that doesn't cater primarily to women—such as a women's dress shop or a beauty salon—needs the signature of a male sponsor.

But Al-Dossary and others are making strides in spite of the barriers—and possibly thanks to some signs of change ahead. The Saudi economy is gradually opening up, as a result of this year's inauguration of the Gulf Cooperation Council's Common Market, which allows citizens of G.C.C. countries (Saudi Arabia, Qatar, Bahrain, Oman, Kuwait and the U.A.E. ) to work freely throughout the region, and the kingdom's accession to the World Trade Organization, which has paved the way for greater foreign investment. Over the past few years, groups like the United Nations have been hammering home warnings on the economic cost of keeping women out of the workplace, citing data such as a 2003 World Bank report on Middle Eastern and North African economies that estimated that the lack of women in the workforce produced a lower G.D.P. for the region by a full 70 basis points throughout the 1990s.