When the Jewish Federation of Greater Washington kicks off its annual fundraising campaign Sunday, it will be appealing to a Jewish population that is larger and younger -- and knows less about the federation's work -- than its leaders realized.

A study released this year showed that the area's Jewish population is the sixth-largest in the country, having grown 63 percent to 110,000 households in the past 20 years, as Jewish communities in New York, Philadelphia and Baltimore showed little or no growth.

But according to the same study, commissioned by the Rockville-based Charles I. and Mary Kaplan Foundation, the Washington federation received less support for local charities and Israeli causes than did federations in other cities with large Jewish communities.

The study's results have prompted federation officials to take a hard look at their organization and consider how to reach beyond traditional supporters. "The study has given us a real mandate to redouble, or triple, our efforts at building community," said Misha Galperin, the group's chief executive.

Historically, the heart of the area's Jewish community has been in southern Montgomery County. But Galperin said much of the new effort will be concentrated in northern Montgomery County, where the number of Jewish households tripled over two decades, and in Northern Virginia, where the number doubled.

As a result of that growth, the area's Jewish community also became one of the youngest in the nation; only 10 percent is older than 65. Federation officials said one key to increasing support will be courting younger Jews who have never heard of the organization, which raises about $20 million locally each year.

The Kaplan study showed that 15 percent of Jews in the area were very familiar with the federation, compared with 56 percent in Baltimore and 26 percent in Atlanta. Many who were aware of the federation were lukewarm about it: Only 20 percent of respondents perceived the Jewish Federation as excellent -- the second-lowest percentage among about 25 other Jewish communities.

Compared with Jews in other parts of the country, relatively few Washington area Jews said they contributed, or were even familiar with, their local Jewish federation -- ordinarily a backbone of Jewish philanthropic life.

The local federation isn't alone in its challenges, said Gary Tobin, president of the Institute for Jewish and Community Research in San Francisco, who studies Jewish philanthropy.

Jewish federations, which raised about $800 million last year, face competition from a proliferation of Jewish charities that have sprung up in recent years, Tobin said. In addition, more wealthy Jewish donors are setting up their own foundations rather than giving through their local federations.

"The fact is that federations don't do the job that they could in reaching out to new donors and cultivating them," Tobin said. "There is still too much of, 'Let's hit 'em and get 'em, and if we can't get 'em, throw them away.' "

About half the funds raised by the 79-year-old Washington federation goes to causes in Israel and about half goes to a network of local Jewish social services agencies, such as Jewish schools, community centers and groups that aid the elderly.

The federation's annual campaign has grown steadily in recent years. Its most recent fund drive raised $22 million, 8 percent more than the previous year and 20 percent more than five years ago.

But the key to increasing those numbers is pulling in the area's newer Jewish residents, said David Butler, a lawyer in the District and the federation's president.

"To me, market penetration is the key to the future growth of our federation," said Butler, who has appointed a commission to examine ways to increase its appeal to area Jews. "It's not going to be just the same people giving more dollars."

To reach out to Northern Virginia Jews, the federation has expanded its office in Annandale and has begun setting up social services in area synagogues. It also has hired a marketing director, is recruiting more volunteers and has expanded the number of "affinity networks" to a dozen. The groups -- for Jewish lawyers, government employees, real estate workers, doctors and dentists -- offer members social events, seminars and networking events.

The expansion is yielding results, foundation officials said. Donations from affinity-network members have grown almost 20 percent since 2001, to $5.1 million.

Jon Lindenberg, 37, a financial adviser who lives in Clifton, said he didn't know much about the Jewish Federation until a friend e-mailed him about it this year.

Since then, Lindenberg has swung into action, forming a "Wealth Advisers" affinity group for the federation in July for financial planners, insurance agents and accountants. It has about 200 members.

Lindenberg said it had been years since he was involved in Jewish activities. Now, he said, "I saw this as a way that I was able to give back to the community and be a part of Jewish life."

Grace Alpert, left, Beatrice Bokrass, Irene Landsman, Joyce Zelinger, Albert Berman and Charlotte Bocknek prepare charity lunches at a Jewish community center in Annandale that is supported by the Jewish Federation.Susan Safran studies Yiddish with a group in Northern Virginia, where the Jewish Federation plans to concentrate its outreach efforts.