Fifteen-year-old Sean was looking forward to his first exchange last summer; however, a day or so after he arrived at the house in Germany where he was to spend the next few weeks, it dawned on him that his German family wasn't quite what he and his parents had been expecting.

That family had just three members: his 16-year-old exchange partner, the boy's father and the father's male lover.

Sean was uncomfortable and embarrassed about a situation he'd never encountered before, but reluctant to upset his parents back in Ireland by telling them about it.

As things turned out, he enjoyed his exchange despite his uneasiness, especially when he and his exchange partner were taken on a holiday by the German boy's stepfather - the man married to the mother, who lived in another city.

Sean's parents didn't hear about any of this until he and the German boy returned home for the second leg of the exchange. They were angry, even though Sean was not deeply upset by the experience. They were angrier still when the Irish company that had arranged the exchange refused to apologise or take any responsibility for - as they see it - betraying their trust.

After many inquiries, they realised that there was nowhere else to take their complaint: the company had broken no rules, because there are no Irish or EU rules governing the activities of private companies that arrange foreign exchanges for students.

Sean's father admits he could be accused of homophobia, but says he believes he and his wife were misled about the kind of family their son would be staying with. Most Irish families, he says, would find what happened unacceptable.

It is estimated that Thousands of Irish schoolchildren, most aged 15 to 17, go abroad every year on foreign exchange or homestay programmes; demand is mushrooming, both for summer and term-time exchanges. Exchanges lasting from as little as six weeks to as much as a year during Transition Year are increasingly popular, with demand for summer programmes is still buoyant.

Of course, the biggest problem most Irish teens will experience is being forced to sit through one-hour meals in France instead of grazing, and not having any night life (many European teens lead more restricted lives than do ours).

Exchanges are organised by a wide and bewildering variety of organisations, individuals, groups, nonprofit and purely commercial private companies and official bodies.

Leargas, which started out running summer exchange programmes as the Youth Exchange Bureau, is now the Department of Education-approved body administering transnational programmes for Government departments and the EU. It is also part of a major EU-funded evaluation of exchange programmes, to be completed next year.

Anecdotal evidence suggests that in the vast majority of exchanges teenagers benefit from experience of a foreign culture, grow in independence, and practise a foreign language. Given the huge numbers going abroad each year, it is surprising that more problems don't surface - but then there is nowhere to go with a problem.

As long ago as 1993, the Youth Exchange Bureau complained that the Green Paper on Education "fails to address quality control for these young Irish people who leave our country on summer exchanges, homestay programmes or school tours. There are several major and many minor operators throughout the country who run exchange and homestay programmes for young Irish people. There is no central register to establish who they are, what they do, the numbers involved, or more importantly, how they carry out such exchanges . . . There exists the potential for mishap or misfortune which may be avoided if operators were requested to operate to minimum standards . . ..the setting up of a register of operators should also be encouraged."

Since then - nothing. The Department of Education has guidelines which schools must follow for term-time exchanges, but takes the view that out-of-school exchanges are not the Department's responsibility.

The bottom line: parents must be vigilant when arranging an exchange - even word-of-mouth recommendations of companies can't be relied on, as Sean and his family discovered. So, what should a parent thinking of sending a child abroad look for?

To find out, I asked various people involved in reputable exchanges: Ann O'Neill, term exchange co-ordinator at Leargas; Bridin Gilroy, project development officer at Leargas; Margaret O'Hehir, senior programme manager of EIL, a long-established nonprofit organiser of homestays abroad; John White, deputy general secretary of the ASTI; Peter Byrne, director of the National Youth Council. Distilled, these are their recommendations:

Find out more about the people or company organising the exchange, How long has it been in the business? Ask the name of its sister company in the foreign country, then check out its reputation by contacting the cultural section of that country's embassy. The Department of Foreign Affairs might help here too, contacting our embassy in that country.

If the outfit organises the travel, ask if it is bonded. (Under Irish travel laws it must be bonded to act as a travel agent, which means the finances must be in order.)

Ask specifically about procedures to select the host family - if someone has visited that family or can vouch for them. (In some cases of school-organised exchanges, the local school vouches for them.) Get the organisation to confirm in writing how it has vetted the family in question. Find out as much as you can about the family, and start a correspondence with them well in advance of the exchange. Get their telephone number, and find someone who can speak with them in their language if you can't communicate with them yourself.

Get the name, telephone number and address of a local contact in the area where your child will be, as well as a national contact: most organisations will have an Irish person in the relevant country, but properly run organisations also have a local contact who keeps a watching brief on the children in his or her area. Be satisfied that the arrangement is closely monitored, and that you and your child have ready access to a local contact. Expect proper advance briefings for you and your child.

Peter Byrne of the NYC is in no doubt that there should be controls "on absolutely anyone who deals with minors". Ann O'Neill of Leargas, who believes passionately that every child should have the opportunity of a visit abroad, believes parents need guidelines.

Concerns about the safety and quality of exchanges shouldn't put parents off considering them, say the experts - it should just make them more vigilant. Indeed, the growing emphasis on learning languages has helped make summer exchanges, homestays and Transition Year exchanges - ranging from £399 to £800 and on up over £1,000 - so popular. There are also opportunities for families who can't afford this kind of money. Peter Byrne of the NYC advises parents to find out what opportunities there are through voluntary organisations, such as youth groups. Under Lingua, an EU programme administered by Leargas, there are funds to subsidise student travel abroad when schools are working on a specific project - up to 75 per cent in areas of disadvantage.