If want to bolster your CV and gain work experience, try a 12-month internship, says Alice-Azania Jarvis

In the States, they've done it for years. College students, at the close of their penultimate year, set off to spend the summer on an internship. They aren't on work experience; they're not there to make tea. Instead, they're treated as trainee staff members and presented with real-world responsibilities.

Rosa Malley, a 24-year-old politics student from Northern Ireland, spent three months with a Washington law-reform group, and was thrown straight in to the deep end. "We had a huge amount of research to do," she says. "They took us really seriously."

"We've found a 25 per cent increase year-on-year in the numbers we place," says Robin Buxton of Placement UK, which matches wannabe interns with their ideal company. And a little practical experience can be invaluable. "Internships substantially increase the chance of finding employment. Imagine if you had only studied theory before taking your driving test."

The most extensive internships can last a full year. So-called "sandwich courses" allow students to take a 12-month break from their studies. It's these internships, says Chris Eccles, managing director of Employment4 Students, where students "really get a feel for the company". What's more, payment starts at £12,000, enabling interns to pay off student loans while they work.

Kate Hindley, 22, was half-way through a degree in marketing and economics at Oxford Brookes when she started a year-long placement at Blueprint Partners, a marketing firm. "I was paid £13,500 and they asked me to come back after graduation," she says. When she did return, she could get straight to work. "I had experience; during the placement, I worked as an account handler," she says. "It was like a graduate job, but they looked after you more."

If taking a year out isn't an option, there's always the possibility of a holiday placement. Plenty of companies offer these; generally over the summer, they last six to 10 weeks. Like the year-long option, holiday interns can earn decent money – the Association of Graduate Recruiters puts the average at £1,200 a month, although that's mostly limited to the financial sector.

For those who can fund themselves, the range of options is broader. And while there's no immediate financial reward, as a career investment the returns are considerable. For one, it's not unusual for interns to return to the same organisation after graduating.

"Placements have become a way to attract the cream of the crop, students whom companies hope will become employees once they graduate," says Buxton. Indeed, the 2007 Graduate Recruitment Survey found that 46 per cent of employers convert a fifth of their interns into permanent staff members.

The competition can be tough, however. Yosuke Homma, 24, hoped his legal internship at Simmons & Simmons would lead to a training contract, but he lost out in the final round. "I was disappointed in myself," he says. "I felt that I hadn't performed." Even without a job offer, internships are advantageous. "I came away knowing that I wanted to work for a large international firm," says Homma. "I've now got a contract with another top firm and my internship helped – it showed I had experience."

As well as bolstering your CV, an internship provides valuable specialist training – particularly for those studying non-vocational subjects, says Homma.

"Having studied biology, interning gave me the opportunity to understand what solicitors did on a day-to-day basis. There was a decent effort at training us, with lectures on professional skills and resources available for research."

If nothing else, then, an internship provides professional kudos. As a senior recruitment officer at Shell, Nimai Swaroop deals with thousands of internship applicants each year. A former intern himself, he's emphatic about the benefits.

"It's a great platform, giving practical opportunities and confidence," he says. "Of the 14,000 applications we had last year, 130 successes came from our internship programme."

Most other recruits, he says, have interned somewhere in the past. "It's become vital for the success of the applicant."