One in nine teenagers have been targeted for sexual grooming in Northern Ireland, a university study said.
Three quarters of them were aged under 16 and many were given drugs or alcohol, the research for Queens University Belfast and the University of Ulster added.
The youths took part in the 2010 Young Life and Times survey.
Director of the research Dr Dirk Schubotz said: "The fact that a sizeable proportion of respondents had been affected by grooming or attempts to take advantage of them sexually, mostly before they had reached the age of consent, reminds us about the vulnerability of young people."
A total of 786 teenagers across Northern Ireland completed the survey. This is the first time in Northern Ireland that sexual grooming and exploitation of teenagers has been included in the study.
Among key findings, the study said that in almost half the cases of grooming the perpetrator was at least seven years older than the victim; one in 15 of those asked said they had been given drugs or alcohol and were then taken advantage of sexually; one in 20 had been offered something in return for taking part in sexual activity. Almost two thirds had not told anyone in authority that this had happened; and over half were initially contacted on the street, through a friend or sibling or in a pub or club with 17% contacted online.