Each year, thousands of college students descend on Washington for unpaid internships. It can be a nerve-racking process: sending out résumés, trying to make contacts, interviewing again and again.

Increasingly, many of them are finding an alternative: paying thousands of dollars to a placement company for a guaranteed spot.

It's a business just starting to appear in other cities. In Washington, it's been thriving for years.

Estimates of the annual number of interns locally range from 20,000 to 40,000. The placement programs provide about 2,500 of these interns, with the number growing each year.

For their money -- often funded with taxpayer-subsidized loans -- students get an internship, housing, night classes, tours of Washington and college credit. But most say they sign up for the work experience.

"I wanted experience. I was worried about graduating and not getting a job," said Brian Schiller, 21, a soon-to-be college senior from Sherborn, Mass., who interned at an executive search firm this summer through the Washington Center for Internships and Academic Seminars. "I needed an internship, and they found me one."

The Washington Center is the city's largest program, and for the past three years it has placed about 1,500 interns annually, up from about 1,300 in 2007. It charges nearly $9,000 for a summer, including housing.

Others include:

-- The Washington Internship Institute. It will place about 200 interns this year, up from 120 in 2007, and charges about $7,000 for a summer.

-- The Fund for American Studies. It has grown from about 370 students in 2005 to 525 this year and charges as much as $7,800 during the summer.

-- The National Internship Program, formerly the Washington Internship Program. It charges an enrollment fee of $3,400 without housing and has seen its numbers increase from 166 students last year to an expected 250 to 300 this year. The for-profit company has doubled its staff in that time and is beginning to expand into other major cities.

"There has never been a harder time to get hired," said chief executive Lev Bayer, whose mother started the company nearly 30 years ago. "There is such a need for internships. We have more students than we can ever deal with."