FAIRFIELD, Conn. -- One winter evening, Priscilla Williams logged on to her computer and sorted through electronic photographs of men who had checked out her profile on the online dating site Match.com: An 80-year-old practicing lawyer, a retired professor, and a Floridian who resembled rocker Eric Clapton.

"The sheer numbers mean that I might meet someone I'm not afraid to bring home," says the 61-year-old widow.

After years of losing subscribers to racier rivals and new social-networking sites geared to young singles, Match has become the largest online dating site in the U.S. by subscriptions, with 1.3 million members. One big reason: older daters like Mrs. Williams.

Match has been reaching out to singles over 50 and divorcees, pitching itself as a destination for mainstream daters who want serious relationships. It made its site easier to navigate for people who are not Internet-savvy, helping people find daters who meet their tastes. The site, owned by Barry Diller's IAC/Interactive Corp., features a free magazine with articles on single parenthood and the love life of Baby Boomers. Its TV ads feature a 71-year-old woman with the user name DanishBeauty22.

The success is a bright spot for Mr. Diller, who is trying to wring profits from IAC's stable of Web businesses. His better-known brands include the search engine Ask, the loan exchange Lending Tree, the invitation service eVite, and the local search site CitySearch. Although Match made up less than 5 percent of IAC's $6.5 billion in sales over the past 12 months, it contributed more than 10 percent of the company's $464 million in operating profit. In the past two years, Match has boosted the number of paying customers by a third.

Match's success in targeting older daters, as well as other overlooked markets such as divorcees and suburbanites, also reflects a maturing Web industry that is expanding beyond its fixation on the very young and tapping other demographics, including the wealthy market of boomers. That's an especially promising strategy for a Web site that depends on fees, not the youth-obsessed ad industry.

AOL co-founder Steve Case this month launched RevolutionHealth.com, a Web site that aims to combine health information and social networking -- particularly appealing to older Americans. Mr. Diller says he is looking at investing in other sites that cater to the over 50s segment online. "There is no question that they are, in size and spending, a very rich vein of opportunity," he said

Older daters "spend more money per month and are more likely to subscribe for a longer period," says Nate Elliott, analyst with JupiterResearch. At Match, 23 percent of subscribers are over 50, more than double the number two years ago. Yahoo Personals has seen double-digit growth in the number of users over 50 in the past two years, thanks in part to a new service that provides extra control, privacy, and security. EHarmony's fastest-growing age group last year was the over-50 segment.

The growing attractiveness of the boomer market means Match may face growing competition as other sites vie for boomer daters. EHarmony, for example, advertises heavily and touts the way it guides communication between potential mates -- a lure for boomers who may be out of practice in the dating market. Match, which powers the personals of the portals MSN and AOL, also runs the risk of spreading itself too thin as it expands overseas while Yahoo focuses on the U.S. market.

Looking for love online is well on its way to becoming mainstream. A 2005 survey by the Pew Internet & American Life Project showed that 15 percent of American adults, or 30 million people, know someone who had a long-term relationship with or married someone they met online, and 31 percent, or 63 million, know someone who has used an online dating service.

At Match, visitors to the site create a free online "portrait" of themselves by posting their photographs, basic information -- build, religion, interests, smoking habits, profession -- and a statement about who they are and what they seek. They can also read the "profiles" of Match's 15 million registered users. But they must subscribe if they want to communicate with any of them, since the profiles are stripped of contact information.

New users pay $34.99 to subscribe to Match for one month, which drops to $16.99 per month if they sign up for six months or more. Match was launched in 1995 and was acquired by Mr. Diller in 1999. As growth declined and competition increased, Match began to mimic rivals' offerings of live mixers, video introductions and searches for jogging partners.

In mid-2004, Mr. Diller appointed Jim Safka, who ran online marketing for AT&T Wireless, to head the unit. The 38-year-old Mr. Safka, who is married and a father of two, set a simple goal: Increase the number of active online daters in each of Match's markets. These daters act as a magnet for other daters, making it easier for Match to attract even more subscribers in those areas.

For three months, Mr. Safka studied subscriber data, combed through financials, and interviewed staffers. Match's data showed him that older daters were more likely to pay to subscribe than the younger daters. Fascinated by that realization, Mr. Safka asked his staff to check the behavior of older daters on the site and to pinpoint their difficulties in using it. For example, many were stopped cold while filling out their online profile by the fourth question, which asked their views on body art and piercings.

The company tested ideas to make the site easier to use, especially for older and less technologically nimble visitors. They developed a variety of one-click buttons: "How It Works" to help new users navigate the site, "See More Like Him/Her" to help users find other candidates that might catch their eye, and most important, a "No Thanks" button to ease the awkwardness of turning down electronic suitors. Mrs. Williams likes Match's "Connections" button, which takes her to a set of pictures of the men with whom she corresponds, before moving onto another button that lets her see who's viewed her profile. "This is where I start" when logging in, she says.

Match hired "Dr. Phil" McGraw, the TV psychologist, who had won the respect of Oprah Winfrey's largely female audience, to develop MindFindBind, an online guide with tips and advice on setting realistic expectations and finding a good partner -- available for an additional $9 per month. Mr. Safka believes that Dr. Phil extends the loyalty of his female, largely older TV audience to the products he endorses, and that creates buzz about Match.com.

"The married viewers refer their single friends, and guys go wherever the women are clustered." Mr. Safka says.

This year, Mr. Safka hired a style maven from the TV show "America's Next Top Model" to launch a free "Portrait ToolKit" to help people upload photos and essays to represent themselves well on the site.

Mr. Safka obsessively checks the numbers of subscriptions by the hour, compared with the same hour in previous weeks, to find any problems with the Web site. He spends an hour a day listening to customer complaints and has all staff trained to do so. The site is policed by a staff of 12, who review each profile before it is posted, removing explicit photos and working to keep out prostitutes, financial schemers, agencies offering foreign brides, and liars.

Just four months after Mr. Safka took over, Match saw a 10 percent increase in paid subscriptions and by early 2005 the number of subscribers topped 1 million. Today, quarterly sales have risen to $80 million, from $50 million when he took over, and operating margins are approaching 20 percent. Traffic to the Match site has increased 18 percent over the past year to 4.3 million unique visitors per month, just short of the 4.5 million monthly visitors to Yahoo Personals -- which has seen its traffic drop 24 percent over the past year, according to the market research firm comScore.

It has produced some happy customers, like Noreen Wald, a 70-year-old mystery writer who uses the pen name Nora Charles. She got engaged this Christmas to a 69-year-old retired U.S. Navy captain she met after a few years of subscribing on and off to Match.com. "It's like window shopping -- you get to see the pictures and read the profiles before you decide if it's a good fit."

But Match's efforts to boost revenue by selling more products on its site doesn't sit well with some users, who resent being solicited on a site to which they have paid to subscribe. Beth Kwon, a 32-year-old editor in New York City who subscribed for several months last year, was turned off by the repeated attempts to get her to sign up for Dr. Phil's. When she tried to take down her profile, she was asked to fill out a questionnaire. "It was like when you're trying to log out of something and it doesn't let you," she said.

Pat Marsh, 55, has had 1,760 men examine her electronic profile and been on half a dozen dates in the five months she has subscribed. But Ms. Marsh says she is ready to quit Match, at least for now. She believes potential suitors regularly use outdated photos, drop 10 years from their age and add $50,000 to their reported incomes.

Mr. Safka is also trying to repeat his stateside success internationally, challenging Match's chief international rival, Meetic, which has 80 percent of the French market and attracts young daters with sexy, fast-paced ads. Based on its experience in the U.S., Match is aiming at over-40s seeking someone to "share life's journey," not younger ones looking for hookups.

The site is also branching out to daters desiring privacy, like executives or teachers reluctant to post their pictures online where subordinates or students may find them. It has introduced Chemistry.com, a premium service that shows a subscriber's profile only to those candidates deemed suitable by a personality test developed by an anthropologist.

Meanwhile, Mrs. Williams, a retired editor of children's publications, continues her hunt for love online. She turned to Match last summer, a year after she became widowed. Since then, she has dated five men from Match, going out six times with one of them. She is currently corresponding with several more, but says she's taking things slowly while getting to know her first grandchild, who was born just before Christmas.

Dating makes her feel her age. Men "all say they like natural looks...but they want no saggy arms, no crepe-y necks, no signs of age or use or experience," she says. She says she has learned to spot men with big egos (they post lots of pictures of themselves) and the ones who might be married (they don't post any pictures).