The Washington Convention Center soon will be the site of a major conference designed to help women business owners tap the multibillion-dollar government procurement market.

The idea for "MegaMarketplace I," to be held April 17, grew out of a similar but smaller meeting sponsored by the Commerce Department last year. The mini-conference paired area women business owners with procurement contractors at Commerce to exchange information about the kinds of contracts available to them.

This year, the conference has expanded considerably to include women business owners from Virginia, West Virginia, Pennsylvania, Maryland, Delaware and the District of Columbia. They will have the opportunity to meet with state, local and federal procurement officials as well as with prime contractors who might be able to offer them subcontracting work. Conference organizers are using a computer to match business owners with specific contractors who will meet with them throughout the day.

Figures compiled by conference organizers show that women-owned businesses -- defined as nonfarm, sole proprietorships -- virtually have been ignored by federal government contractors. In fiscal 1984, figures show that only seven-tenths of 1 percent of all federal prime-contract dollars went to women business owners. Women-owned businesses in the service industry netted a slightly larger share, with eight-tenths of 1 percent of the total.

Nonetheless, during the past six years, the number of women-owned businesses in the country has grown rapidly. Internal Revenue Service statistics show that, between 1977 and 1983, the number of female business owners rose from 1.9 million to 3.3 million.

Commerce Department spokeswoman Susan Solomon attributed the lack of government contracts for women to the limited amount of time these companies have been competing in the marketplace. The conference will allow them to market themselves in a field where they have had very little exposure, she said.

Thus far, 500 women have signed up for the conference, representing a myriad of businesses from software programming and construction to financial services and exercise instruction.

"What we are doing here is breaking into hard-to-tackle networks like the old-boy network that have existed for years," said Gillian Rudd, president of Levine and Rudd Marketing and head of the Capitol Charter of the National Association of Women Business Owners, one of the sponsoring organizations.

Rudd, who was responsible for inviting prime contractors to the event, said that many people in government procurement fields are not aware of the enormous number of women that have become involved in business over the past 10 years. She said the conference would be a good time to introduce the two groups.

The conference was initiated through the Women in Business Advisory Committee to Councilmember Charlene Drew Jarvis with the help of Katherine Bulow of the Commerce Department, Janice Wolfe of the Small Business Administration and Rudd.

Sponsoring organizations include NAWBO's national chapter, the SBA's Office of Women's Business Ownership, the Commerce Department, the Committee on Housing and Economic Development of the District of Columbia and the Office of the Deputy Mayor for Economic Development for the District.

Several towns in the mid-Atlantic, including Baltimore, have shown support for the program by declaring April 17 "Women Entreprenuers: Government/Business Opportunity Day." Solomon said her office already has received calls from women business owners in the Southwest and Midwest asking them to sponsor a similar program there. TRADE

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At the March 4 annual meeting of the Northern Virginia Clearinghouse Association, Brian C. Middleton, an operations manager for the Greater Washington Region of the United Virginia Bank, was reelected president. Michael G. Anzilotti of First Virginia Bank was selected vice president, and Walter A. Howell of Riggs National Bank was selected secretary/treasurer. In addition, William C. Calvert was elected manager of the clearinghouse, replacing Michael J. Umlauf, of First American Bank of Virginia, who had managed the clearinghouse since it was formed in 1981. PROFESSIONAL

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