One in 11 teens has been the victim of physical dating violence.
One in four teens report being emotionally or verbally abused by a boyfriend or girlfriend.
The danger to teens in these high-risk relationships often goes unnoticed, even by the adults who surround them.
In Harrisburg, Dauphin County, a ceremony is performed in memory of victims of domestic violence. For every name engraved, thousands of others may be living in silence, many of them under 18.
"One time after a fight, he grabbed my arm and you could see four black and blue marks from his fingers,” remembers Genna Willey.
At age 17, Willey’s first love became verbally and physically abusive. When she tried to break up, her boyfriend became enraged.
"He strangled me against the wall, [and] put his hands against my neck," she said. "Then he punched me in the leg, he kicked me, [and] he punched me in the head to knock me out."
Willey managed to break away. A friend called her family, who then called police and rushed to their daughter’s aid.
"I really didn’t think that someone of that age was capable of putting harm to someone else that they thought they loved,” said Karen Willey, Genna's mother.
Jennifer Storm is the executive director of the Pennsylvania Witness Assistance Program.
She said signs of domestic violence are often subtle, especially in teens.
“It's so hard to decipher what is normal adolescence angst, and what is something that could be a red flag,” Storm said.
Parents should watch for changes in a teen's mood, sudden weight loss, and isolation.
Also, changes in social media habits could provide important clues.
An abuser may force a victim to limit interaction with friends: in person, on the phone, or online.
"Whether it’s verbal, mental, or physical, abuse is abuse and it can only escalate and I wish I would have known," Genna Willey said.
There is a growing national effort to educate young people about dating violence.
At least 19 states have mandatory dating violence awareness programs in public schools, with lawmakers in several additional states considering legislation to implement educational programs.