The research, described as the first national look at sexual orientation and teen punishment, comes as a spate of high-profile bullying and suicide cases across the country have focused attention on the sometimes hidden cruelties of teen life.
The study, from Yale University, adds another layer, finding substantial disparities between gay and straight teens in school expulsions, arrests, convictions and police stops. The harsher approach is not explained by differences in misconduct, the study says.
"The most striking difference was for lesbian and bisexual girls, and they were two to three times as likely as girls with similar behavior to be punished," said Kathryn Himmelstein, lead author of the study, published in the journal Pediatrics.
Why the punishment gap exists is less clear.
It could be that lesbian, gay and bisexual teens who got in trouble didn't get the same breaks as other teens - say, for youthful age or self-defense, Himmelstein said. Or it could be that girls in particular were punished more often because of discomfort with or bias toward some who don't fit stereotypes of femininity.
"It's definitely troubling to see such a disparity," Himmelstein said.
"It may very well be not intentional," she said. "I think most people who work with youth want to do the best they can for young people and treat them fairly, but our findings show that's not happening."
The punishments can be damaging, she said. Teens expelled from school have higher dropout rates, and involvement in the criminal justice system can affect a range of opportunities, including housing eligibility and college financial aid.
"I find it tragic, " said Clara McCreery, 18, co-president of the Gay-Straight Alliance at Walt Whitman High School in Bethesda. "I wonder if some people misinterpret the way some gay girls choose to dress as a sign of aggression."
Stacey Horn, an associate professor of educational psychology at the University of Illinois at Chicago, called the study important and compared the findings to racial disparities in criminal sentencing. "To me, it is saying there is some kind of internal bias that adults are not aware of that is impacting the punishment of this group," she said.
The study brings punishment differences for gay teens into focus at a time when public concern about torment and bullying is heightened. In September, an 18-year-old Rutgers University student jumped off a bridge to his death after his gay sexual encounter was allegedly filmed by a roommate on a webcam and announced on Twitter.
Probing the consequences of teen misconduct, the new study examines behaviors that include lying to parents, drinking, shoplifting and vandalizing, as well as more serious offenses such as burglary, drug sales and physical violence.
Using data from more than 15,000 middle school and high school students who were followed into early adulthood as part of the National Longitudinal Study of Adolescent Health, researchers compared categories of misconduct against six punishments. The interviews used for the study started in 1994-95 and continued until 2001-02, but researchers said they expect the findings would be similar today because the institutions involved have not dramatically changed.
Nearly 1,500 of the participants in the study identified themselves as lesbian, gay or bisexual, but more than 2,300 reported having felt a same-sex attraction at some point in their lives. More than 800 were in a same-sex relationship.
The results showed that, for similar misconduct, gay adolescents were roughly 1.25 to 3 times more likely to be sanctioned than their straight peers.
The sexual-orientation disparity was greatest for girls. Girls who identified themselves as lesbian or bisexual experienced 50 percent more police stops and reported more than twice as many juvenile arrests and convictions as other teen girls in similar trouble, the study said.
Andrew Barnett, executive director of the Sexual Minority Youth Assistance League, which serves 300 teens a year in Washington, said he was not surprised by the findings.
"This is a symptom of school administrators, teachers, court officials, police officers - anyone who works with youth - not necessarily being equipped to handle the challenges" faced by the teens in their care, he said. "It's much easier to punish the youth than to work with them and figure out why they may keep getting in fights and what is leading to this behavior."
Hien Le, 17, president of the Gay-Straight Alliance at Montgomery Blair High School in Silver Spring, said she sees no tendency to punish gay students in her school. But she and other teens said parents often become more punitive when they disapprove of a son or daughter's sexual orientation.
"Your parents are the ones who are supposed to be supportive, but it isn't always that way," she said.
"I think it happens more than people think," said Caroline Callahan, 16, president of the Gay-Straight Alliance at Langley High School in McLean.
The study's data set was not large enough to allow for an additional analysis by race, but Himmelstein and others said that was an important area for further study.
Jody Marksamer, a staff attorney and youth project director at the National Center for Lesbian Rights in San Francisco, said the study brings data to what advocates have seen for years: that biases, overt and subtle, often play out in courts, in schools and with police.
Gay youths are often grappling with family tensions and harassment by peers and sometimes with depression or homelessness, he said. Harsher punishments can make for "a cascade of effects" that can "move them from the schools to the criminal justice system."
Joseph Kosciw, senior director of research and strategic initiatives of the Gay, Lesbian and Straight Education Network, said that more needs to be done in schools. "I think it really calls for professional development about how to address" issues related to sexual orientation, he said, "and how to address bullying and harassment when they happen."