More than half the girls reported physical violence in at least one of their relationships.
Interviews with 44 boys and 38 girls aged 13 to 18 - who were not in mainstream school - found physical, emotional and sexual abuse was common.
More than half the girls said they had been in a sexually violent relationship before they were 18.
A quarter of boys said they had dated physically aggressive partners.
More than half of the girls reported that they had been a victim of physical violence in at least one of their intimate relationships.
Two-thirds of the girls interviewed and a third of the boys reported experiencing emotional violence, most commonly controlling behaviour.
The report, called Standing On My Own Two Feet, contacted the 82 young people through a range of agencies and organisations working with disadvantaged young people across the south-west of England.
Some of the teenagers interviewed had been permanently excluded from school, were young offenders or teenage mothers.
Forced to have sex
Emma, who was interviewed for the study, told researchers how she had been forced into having sex "quite a few times" when she was 13.
"I've never shouted rape or anything. I've never been able to say that I've been raped but it's not like I've given consent. In certain situations it has been pushed on me and it has been really horrible."
Ellie told researchers: "He [boyfriend] was really persistent... he like held my hands up against the wall, and I was like, 'Seriously get off, I don't like want to'.
"And he was like 'Oh no, come on, it'll be fun, it'll be like a laugh' and stuff. And so he did and I was just like... I don't know, 'cos it really hurt.
"It was horrible, and so I just laid there like crying, like tears running down my face."
Fourteen-year-old Jo said her boyfriend had "only hit me in the face once".
"He used to push me down the stairs and stuff though."
Sasha, who has been in care, said: "I felt I had to do it… like a friend would say to me 'Just do it' and stuff like that.
"Sometimes the boy would say 'Oh just do it' and like go on and on. I'm just like 'OK'."
While half of all those taking part in the research had been assigned a social worker, most did not reveal their partner's violence. Many said welfare professionals were not interested in this aspect of their lives.
"Control and violence seem to be so prevalent in these relationships that girls are unable to recognise its impact"
Christine Barter Report author, Bristol University
The study follows on from a survey in 2009 - also by Bristol University on behalf of the NSPCC - of 1,400 girls aged 13 to 17, who were not considered to be from vulnerable backgrounds.
It found a third suffered sexual abuse in a relationship and a quarter experienced violence at the hands of their boyfriends.
'Child welfare issue'
Christine Barter, from Bristol University, who led this latest research for the NSPCC, said: "Tragically, control and violence seem to be so prevalent in these relationships that girls are unable to recognise its impact - it is an everyday happening.
"Many girls found it very difficult to see that their partner's behaviour is abusive. The government and those working with young people need to recognise that teenage partner violence is an even more profound child welfare issue for disadvantaged young people.
"This will help professionals assess the possibility of partner violence and challenge young people's beliefs that this abuse is a normal part of teenage relationships."
Andrew Flanagan, chief executive of the NSPCC, said: "It's appalling that violence in these relationships seems to be just part of daily life.
"These findings underline how important it is for children to be educated about abusive behaviour and for them to feel able to seek help to prevent it happening."
Home Office Minister Lynne Featherstone said: "We need to challenge the attitudes and behaviours that foster an acceptance of abusive relationships by intervening as early as possible.
"Bringing the issue out in the open will help teenagers feel confident to challenge abusive behaviour when they experience it or see it."