More than a third of children sexually assaulted or raped are attacked by another minor, it has emerged.
Research has revealed 37% of all perpetrators of child sexual violence are under 18 and more than half are a friend, acquaintance or neighbour.
Another quarter are related to their victim, and 97% are male.
The statistics were revealed by Rape Crisis Network Ireland (RCNI) and Children at Risk in Ireland (CARI), which analysed 200 allegations made by 192 children and teens they supported last year.
Fiona Neary, RCNI Director, said the rate of sexual abuse by children has been underestimated up to now.
"We do our boys and young men a grave disservice if we do not talk to them about consent, sexual activity and sexually harmful behaviours in a sustained and structured way at every opportunity afforded to the state and society," she said.
"If we do not support, challenge and educate the boy child, we fail both the boy and the girl child.
"This is a much more valuable focus that teaching 'stay-safe' lists for girls, which are often impossible to achieve and can result in victim blaming attitudes."
The study of 16 support centres found:
:: young children are most vulnerable to sexual assault, perpetrated over many years by a male family member in their home.
:: teenagers are more likely to be raped by a friend or neighbour over a number of hours outside the home.
:: 75% of girls and boys aged 13-17 had been raped.
:: 70% of children were under the age of five when first sexually assaulted.
:: 73% of girls aged 13-17 were abused outdoors or away from their home, with 85% stating the attack lasted hours.
:: six out of ten child survivors also experienced other forms of violence.
:: the average age of the perpetrator was 26 years and 98% were male.
:: child perpetrators abused those of similar age or younger who were usually non-family members.
The study, Hearing Child Survivors of Sexual Violence: Towards a National Response, will be launched today by Children's Minister Frances Fitzgerald.
It is said to provide new data which can reduce child sexual violence crimes and protect vulnerable children more effectively.
CARI's Mary Flaherty called for a national service for the growing numbers of children who are reporting abuse each year.
"It is clear that adults' services are trying to meet the needs of children as young as 14 due to the absence of any alternative," she added.
"The report also highlights the fact that much abuse is perpetrated by young people themselves.
"This corresponds to a marked increase in referrals to CARI to work with children who engage in sexually harmful behaviour."