Many of the Washington area's gay male and lesbian couples are middle-aged suburban homeowners, according to a new study of census data that offers the first detailed portrait of one of the nation's largest gay communities.

The study indicates that half the area's men and women in gay couples are 39 or older, six in 10 households own their own homes and nearly one in three gay couples has lived in the same house together for five years or more. By those measures, gay male and lesbian couples are less settled than married couples but are more so than unmarried heterosexual couples. The trend holds true nationwide.

"A large proportion [of gay couples] are committed, a large proportion own their own home, a large proportion have children," said Urban Institute demographer Gary Gates, who compiled and analyzed the figures for the Human Rights Campaign Foundation, an offshoot of the advocacy group.

One reason gay couples seem less rooted than married couples is that some of them are experimenting with living together, just as heterosexuals do, said M.V. Lee Badgett, a University of Massachusetts economist who studies the gay population. She said that as a group, gay men and lesbian couples are more rooted than unmarried couples because some are longtime partners who would wed if the law allowed.

Washington area gay couples also have higher incomes, are more likely to be working and are better-educated than all same-sex couples nationwide, reflecting the region's affluent culture. They are somewhat less likely to work for the government than married people are. Locally, gay male couples own more expensive homes than married couples do, but that is not true nationally.

The 2000 Census counted 15,000 same-sex couples in the region and 600,000 nationwide. The Washington area ranked fourth -- behind San Francisco, New York and Los Angeles -- in the number of heavily gay neighborhoods, with the District, Arlington and Alexandria ranking high.

Nationwide, the numbers show, gay couples are more often from different racial or ethnic backgrounds than are married couples. Lesbians are four times as likely as married women to have served in the active-duty military, National Guard or reserves.

The region's gay population has grown in political clout, is increasingly living outside the best-known gay neighborhoods and is affluent enough to support a growing number of businesses. A business directory aimed at gay men and lesbians called "The Other Pages" has 16 pages of listings for real estate agents, some of whom advertise themselves as being gay.

David Kempton is a home inspector who lives in Springfield and owns two homes with his partner of six years. He says the gay community accounts for half his business, and that proportion is rising.

"The gay community strives hard at feeding their own," said Kempton, 44. "They are very loyal. When I and my partner are looking to have something done, that's the first place we look, to keep our money in our community."

Michael Smith and his partner of two years, Michael McVey, run a Dupont Circle printing business that does a substantial amount of work for gay-owned businesses, including local restaurants and bars. Now that commitment ceremonies are becoming more popular, the couple are considering putting together some sample invitations and announcements, such as those offered for engaged couples.

"Everybody thinks we're promiscuous for one, and can't hold a relationship," said Smith, 40. "We are a lot more stable than people realize."

The Washington area census did not ask about sexual orientation, but it offered people the option to call themselves an "unmarried partner" of someone in the same house, and some described themselves as a same-sex spouse. Gates's analysis included a local sample of 172 gay men and 144 lesbians. The census numbers are not a complete count: Advocates say some couples did not identify themselves on the census form, and the data do not include the estimated two-thirds of gay men and lesbians who are not in couples.

By some measures, gay couples are distinct. Despite a "gayby boom," a previous report based on the 2000 Census showed they are less likely than other couples to have children at home: One in three same-sex female couples has children, as does one in five same-sex male couples. The new numbers show that more than half have a college degree, making them more highly educated than other couples.

Gay male couples have higher household incomes than married couples do. Gates said gay male households have higher incomes than married ones because both partners are more likely to hold a job, and because men earn more than women. His analysis shows that gay men have lower earnings than married men, which other studies also have found.

One reason, he said, could be that gay men often choose a lower-paying workplace because it is gay-friendly. But Gates said the earnings gap is smaller in states with laws prohibiting discrimination against gays, a finding that is especially true for men without a college degree.

Lesbians who have partners earn more than married women, the census numbers show, in part because they are more likely to work full time.

The Human Rights Campaign said it plans to use the figures to lobby for stronger anti-discrimination laws and policies.