When engineer Zarik Boghossian felt tapped out at his job, he turned to an employment firm to help him find a new one. But after paying $5,000, he says he got little more than outdated contacts, job leads that were widely available on the Internet and a 300-page "customized" document with standard career advice.

So when a colleague invited him to join LinkedIn.com, an online social network where professionals can meet peers and make career contacts, he gave it a try. Within a month of joining in April, Mr. Boghossian spotted an intriguing profile -- Afshin Behnia, chief executive of Mitratech Inc. He met with this new contact and landed a job as vice president of engineering at the Los Angeles technology and services company.

"Next I want to be a president or chief executive officer of a company," Mr. Boghossian says. "I think I can get there by [online] networking."

A growing number of professionals from Los Angeles to Lyon to Lijiang are taking Mr. Boghossian's path, using online social networks to build up a list of contacts -- and potentially land a dream job. Unlike regular employment sites, which mainly list want ads and applicants' resumes, social networks are designed to be, well, more social.

When job seeking, the idea isn't necessarily to search for a specific opening -- instead, you look for other members who have a common friend or interest. From there, you build a relationship by e-mail and interviews, just as you would in traditional networking.

Fans of the networks claim that the personal connection with other members gets them access to choice jobs that don't show up in want ads. And, as in the case of Mr. Boghossian, fans say that the networks can put them in touch with top executives, instead of just the human-resource officials they'd reach through an ad.

The online networks "enhance what we've always done and empower us to do what we've always imagined we could do -- if we were naturally great networkers," says Gerry Crispin, principal at CareerXroads, a recruiting-technology consulting company in Kendall Park, N.J.

Getting Started

Professionally oriented social networks have existed for years. But only in the past 18 months have their numbers boomed. Why now? In part, it's because of the runaway success of Friendster.com, a network that lets you meet new people through others whom you know in common. Launched in March 2003, Friendster drew millions of members within months. The site's focus is purely social -- but it got people thinking that the Internet could help them improve their professional life as well as their private life.

To be sure, networks are used for a host of business purposes. Many users aren't even there to find jobs -- they simply list themselves to form relationships in their field.

Getting started on professional networking sites such as LinkedIn Ltd.'s LinkedIn, Ryze Ltd.'s Ryze.com and IAC/InterActiveCorp.'s ZeroDegrees.com usually goes like this: A user signs up, creates a password and fills in a career profile. Many people are invited to join by friends who already belong, but most sites also let users join on their own.

Users can usually choose from a host of privacy features so that, for example, their contact details aren't visible, or are visible only to people they designate. Some sites are free of charge, others charge fees for certain services (such as contacting other members), and a few are closed except to paying customers.

Once users join the network, there are two basic ways to search for contacts. First, they can trawl for people based on a host of factors, such as name, industry or location. When they spot a likely profile, they send an e-mail explaining who they are and what they have to offer, and perhaps requesting a real-world conversation. In some cases, the site acts as intermediary, hiding both parties' e-mail addresses until they agree to share them.

Most people, however, will want a referral from a third party. In that case, the approach to take is to build up "connections." In other words, users look around for people they know on the network and send out invitations to "connect" to them. The friend who gets the invitation clicks on a link that confirms that he or she knows the user. As soon as that happens, the user can more easily request contact with all of the friend's friends -- and so on.

The more connections you have, the more friends-of-a-friend you can meet, and the better your chances of finding a useful contact. A user's profile generally lists how many connections he or she has; most sites let users mask the identity of those contacts from casual browsers.

After you've established some connections, how you make contact with a friend's friend depends on the network. On LinkedIn, these requests must almost always go through the people to whom the job seeker is connected. Each person in the line of acquaintance often adds a comment about the seeker. For instance, "Sue, who I used to work with, is interested in your company -- she was quick and efficient in our R&D lab, so I'd be happy to recommend her work."

In some cases, these sites also host job listings. Members of Tribe Networks Inc.'s Tribe.net can access 25,000 job listings daily from a variety of sources including CareerBuilder.com, while LinkedIn, of Mountain View, Calif., carries listings from DirectEmployers.com. And ZeroDegrees, of West Hollywood, Calif., plans to add a job-listing section to its site before year end. (Warning: The site currently supports only Windows users.) Monster Worldwide Inc., of Maynard, Mass., officially launched Network.monster.com in April, adding networking features to its popular job-listing site.

In other cases, networking sites offer offline events so members can mingle and hear directly about job opportunities. Career Change Network's CareerChangeNetwork.com, Ecademy Ltd.'s Ecademy.com, ExecuNet Inc.'s ExecuNet.com, OpenBC.com (run by Open Business Club GmbH of Hamburg, Germany), Ryze and Tribe.net all host social functions or have online features where members can organize and advertise events.

Even sites not usually thought of as business networks can be useful for job seekers, as long as members list their company name in their profile. At Classmates Online Inc.'s Classmates.com -- where people are more likely to search for a kindergarten sweetheart -- there's a section called Work & Careers where members can look for acquaintances by company from among the network's millions of members. The site, based in Renton, Wash., can be quite handy when interviewing at a company where you think you don't know anyone.

The Old-Fashioned Way

Of course, many experts stress that job seekers should use online tools to complement, not replace, traditional efforts. Moreover, for all the success stories, job networks aren't an instant fix. They can take months to pay off, and many users have to try several sites before finding one that matches their preferences. Plenty of other people simply haven't found the sites useful and wonder why they bothered to join in the first place.

Still, many users report that networking sites have helped them out of job-search jams that would be tough to solve with traditional methods.

Jodi Leslie Ravel, a public-health executive, was recently between jobs when her job at a Los Angeles agency ended earlier than expected. She still had months to go before a planned move back to the San Francisco Bay area, and she needed work in the meantime. Checking on Tribe.net -- which she had been using mostly for social purposes -- she noticed that a friend of a friend was looking for someone to help with odd jobs related to television documentaries.

It wasn't her field, but she says she didn't hesitate to apply for the job because of her connection to the potential employer. "It was a world I knew nothing about," says Ms. Ravel, adding that she enjoyed her work editing scripts for a half-dozen documentaries before moving north to her next job.

(There are, in fact, social networking sites that help people examine their career choices and look for work outside their field: Tickle.com -- run by Tickle Inc. of San Francisco, which Monster bought in May -- offers career tests for assessing job preferences and abilities, while CareerChangeNetwork, of New York, connects members in a given profession with people who want to switch to that profession.)

Moreover, employers say that job networks can help bring in better candidates than online job boards. Many companies, for example, prefer to recruit people who already have jobs -- and those candidates usually don't peruse Internet want ads or post their resumes online. But they will often put their profile on social networks to build contacts in their field.

For example, in January, Ted Smith, senior vice president of business technology at CNET Networks Inc., spotted the profile of Don Marzetta on LinkedIn.com. Mr. Marzetta wasn't actively looking for a new job but had indicated in his profile that he was open to offers while running his own consulting firm in San Francisco. Mr. Smith soon hired him to manage the integration of content from computer companies into CNET's site.

"There are so many active job seekers on the market -- the candidate pools are so large it's hard to find a diamond in the rough," says Sala Baker, manager of corporate staffing at home-improvement retailer Home Depot Inc. in Atlanta. Online social networking "gets at the passive job seeker."

Other employers say social networks are a good way to get referrals from people they know and trust. Many networks also let acquaintances post endorsements for people they've worked with.

"LinkedIn.com is changing the way we recruit," says Anne de Kerckhove, chief operating officer at Inspired Broadcast Networks, a two-year-old London-based broadband entertainment and services firm with about 100 employees. "People who come recommended are often much better than through a headhunter."

Getting Specific

Networking sites can also make it easier to target contacts by a particular industry or interest. AlwaysOn Network LLC of Woodside, Calif., runs a site that combines a social network -- called My Zaibatsu, a Japanese word that suggests intertwined companies -- with user-posted commentary directed at technology-industry executives and investors. So the site, always-onnetwork.com, might be a good bet if you're looking for a job at a venture-funded tech start-up, says Chris Selland, a vice president at consulting firm Aberdeen Group Inc. in Boston.

Ecademy, based in Haslemere, England, is a network focused on small businesses, while ExecuNet, of Norwalk, Conn., focuses on executives with an annual salary of $100,000 or better. San Francisco's Tribe.net is a hybrid social/professional network that can be a good place to look for contract work -- particularly in creative professions such as photography -- and other temporary jobs.

Selling Yourself

Spoke Software Inc.'s Spoke.com, meanwhile, is a favorite of salespeople, since the company offers relationship-management tools for sales forces. Before a recent job interview at BDNA Corp., Mike Milton used Spoke, of Palo Alto, Calif., to find out professional information about the people the company said he would meet during the interview. He credits the site with helping him get the marketing job he now has at the Mountain View, Calif., firm, which helps companies track and control spending on technology assets.

Many sites, such as Ryze and Tribe.net, also let members form online interest groups based around geographical or professional interests and other factors. So, for example, you could peruse those groups to find a contact in a particular part of the country, or one who went to the same college as you.

Two years ago, when Tim Redhed was moving from Silicon Valley to Las Vegas, the first place he looked for work was Ryze. After contacting one of the eight Las Vegans on the social network at that time, Mr. Redhed got a job interview. By January of 2003 he was a senior buyer at Your Buyer Inc., a purchasing-services company in Las Vegas.

Today, Mr. Redhed could wander farther from home and perhaps get similar results: Ryze, based in San Francisco, boasts members from more than 100 countries. About half of LinkedIn's one million members are from outside the U.S.

Meanwhile, 65% to 70% of Ecademy's membership is based in the U.K., but the firm launched a site for the U.S. in May and sites for India, Japan and other Asian countries in July. France's ViaDuc.com, run by Agregator SARL of Paris, covers French-speaking professionals, while Germany's OpenBC operates in five languages and is gaining users from around Europe. The company also plans to launch shortly a site for the Chinese market.

The international reach of networking sites can lead to unexpected opportunities. A friend of Loïc Le Meur, a Paris-based executive vice president of Six Apart Ltd., which makes tools for bloggers, was recently browsing through Mr. Le Meur's network on LinkedIn. The friend, who wanted to expand his business in China, noticed a profile of someone in China who had exactly the sales experience that he was looking for. From Paris, Mr. Le Meur introduced the two through LinkedIn -- and with a single geste fulfilled the employment needs of two friends.