A third of Northern Ireland teenagers know another young person being harmed through bullying, parental fighting or self-inflicted harm, according to a new survey.
The NSPCC launches a public education initiative
However, it found most teenagers who knew a friend being harmed had not told an adult about it.
The NSPCC survey, published on Tuesday, showed children instead chose to confide in other friends.
But if a friend confided in them about a harmful experience, one in four would not do anything about it, said the charity.
The findings coincide with the launch of NSPCC Northern Ireland's next phase of its campaign to give children and young people someone to turn to.
It is a public education initiative to encourage every child to speak to someone they trust if they are worried about anything.
New resources for schools, fundraising initiatives and a call for increased peer support schemes in schools form the basis for the campaign.
It will include Someone to Turn To talks for secondary schools.
The NSPCC's director in Northern Ireland, Ian Elliott, said: "Vulnerable young teenagers are being exposed to many serious, sometimes life-threatening situations.
"However, by confiding in their friends they are not always getting the help they need."
Aisling McElearney, the charity's education adviser, said: "Every child needs to have someone they can turn to, someone who will listen, take them seriously and provide advice and support.
"Peer support does that by helping to get problems out and into the environment in which others can help.
"It gives children the opportunity to talk to someone about anything that is worrying them and can identify a cause of the problem.
"Some problems need more than someone to just listen. Peer support really can provide that bridge between listening and getting a young person the help they need."