A company opens its doors in the Washington area. It sets up phone lines, hires people, hooks up computers and advertises. And somewhere along the line, its executives often start wondering: Should we join a chamber of commerce, and if so, which one?

The decision can be daunting in this region, which offers roughly five dozen choices. Including countywide and city chambers, companies have their pick of eight in Fairfax County, eight in Montgomery County, four in Prince George's County and two in the District. Even a locality as tiny as the 2.2-square-mile city of Falls Church has its own chamber. And that's in addition to the U.S. Chamber of Commerce, the state chambers, and chambers that form around racial and ethnic interests.

To help companies find the best fit, Barbara B. Lang, president and chief executive of the D.C. Chamber of Commerce, advises them to consider two key questions: Where is your base of operation? Where are you trying to do the most business? Pick the chamber that develops the relationships your company needs to succeed.

"Joining a chamber should not be a charitable or philanthropic type thing," Lang said. "There has to be a value proposition for these businesses. For their investment, they should get something in return."

That return can include networking opportunities, educational seminars and free advertising in a chamber's newsletter. But what makes a chamber a chamber is its designation as a 501(c)(6) organization, which grants it the ability to lobby on behalf of its members. The larger the group, the greater its clout.

Still, companies must consider where they want that clout. For example, the influence the U.S. chamber has in Congress or the muscle the Virginia Chamber of Commerce flexes in Richmond is of little use to Robert Young, a developer in McLean who needs various zoning approvals from local officials.

Years ago, Young Group Inc. joined the local chamber in McLean, where most of its projects were. When the work in McLean ended, so did the firm's membership in the chamber there, he said. And when the company picked up jobs in the city of Falls Church, it enrolled at the Greater Falls Church Chamber of Commerce.

"Whatever community we're developing in, we need to be a part of that community in as many ways as possible," said Young, now a board member of the Falls Church group.

But a company, especially a large one with deep pockets, need not limit itself to one chamber.

Best Buy Co., the nation's largest consumer-electronics retailer, recently joined about 20 chambers in Virginia to promote its "Best Buy for Business" service, said Luis Castillo, business sales manager at the store in Falls Church. The service offers reward programs and around-the-clock computer support to companies with up to 20 employees. To market the program, Best Buy hosts in-store "mixers" for chambers, advertises ribbon-cutting ceremonies in chamber newsletters and sponsors chamber events.

"The idea is not to say, 'Here we are, come shop with us' because the majority of chamber members already know who we are," Castillo said. Rather, the goal is to sell a specific service to a niche audience. "Every time we open a Best Buy for Business location, we have to be part of the chamber there and in some cases, more than one."

No matter how many chambers a company joins, or where it joins them, a key factor in the decision is the elbow-rubbing factor. In other words, who do company officials most want to meet?

For P. Wesley Foster Jr., chairman and chief executive of Long & Foster Cos., the answer was the Washington region's movers and shakers. That's why his company joined the Greater Washington Board of Trade, a District-based chamber that represents 1,100 mostly large companies in suburban Maryland, Northern Virginia and the District.

"I want to know all the players in the region, in D.C., in Montgomery County, in Prince George's County, in Northern Virginia," Foster said. "I want to know who they are, how they function, what they do."

The networking paid off personally and professionally, he said. "I was able to find out firsthand when new corporations were moving to the Washington area so we got a shot at them first," Foster said. "We got a shot at selling their people homes, and when we were heavily into the commercial space, we got a chance to rent them space and sell them buildings."

Chambers are nonprofit organizations. But like most businesses, the need revenue to operate and they get it from membership dues and corporate sponsors, which pay to have their names emblazoned on banners at golf outings or black-tie dinners. To stay relevant, chambers must boost their membership bases in an increasingly competitive field.

With that in mind, the Fairfax County Chamber of Commerce reorganized itself three years ago, creating four councils that cater to specific interests, such as government contracting or international business. "That gives us focus in our programming and advocacy efforts," said president and chief executive William D. Lecos. "Before, we had a one-size-fits-all approach."

Usually, dues are charged based on the size of the company. At the D.C. chamber, dues begin at $350 a year but the chamber spends $950 annually supporting each business with seminars, newsletters and information, Lang said.

She tries to bridge the gap by making marketing deals. At some office-supply stores, chamber members get discounts and the chamber makes a bit of money on each order. Soon, the chamber might even put its name on MasterCard and Visa cards.

"Just because we're a nonprofit, it doesn't mean we want to zero out by the end of the year," Lang said. "We ought to be making money so we can remain financially stable. I'm all about doing that."