Some psychologists blame the increase in numbers — 40 percent over two decades — on a society saturated with sex and violence and the fact that many of the accused were themselves victims of adult sexual predators. Others say there aren't more children committing such crimes, simply more awareness, better reporting and a general hysteria about sex offenders.
"I don't think it's appropriate to suggest we have whole schools full of sexual predators ... but we're seeing more of it and more sexually aggressive acts," said Scott Poland, past president of the National Association of School Psychologists. "How do these kids even know about this? It's permeated throughout our society."
Robert Prentky, a psychologist and nationally renowned expert on sex offenders in Bridgewater, Mass., thinks the statistics are misleading.
"There aren't more kids, there are more laws," he said. "We now have fairly draconian laws with very harsh sanctions that apply to juveniles."
The number of children under 18 accused of forcible rape, violent and nonviolent sex offenses rose from 24,100 in 1985 to 33,800 in 2004, the AP's analysis found. Violent offenses include attempted rape and sexual assault, while nonviolent offenses including fondling, statutory rape and prostitution.
By comparison, rape and sexual assaults by adults decreased more than 56 percent from 1993 to 2004. Comparable statistics were unavailable before 1993.
The AP analyzed state and federal crime statistics, as well as independent research on juvenile sex offenders. Sources included the U.S. Department of Justice's Bureau of Justice Statistics; the National Center for Juvenile Justice, a Pennsylvania-based nonprofit that specializes in statistical and policy research; and The Safer Society Foundation Inc., a Vermont nonprofit that works to prevent sexual abuse.
Sharon Araji, an Alaska psychologist who took one of the first broad looks at the problem in her book "Sexually Aggressive Children," thinks the number of child-on-child sex crimes is actually even higher than the statistics indicate.
Only 28 percent of all violent sexual assaults are reported to police, according to a 1999 National Crime Victimization Survey. And cases of incest between siblings are widely thought to be underreported and may drive the numbers even higher, Araji says.
"The whole society is not yet up on this problem," Araji said. "These kids, on the extreme end, if nothing is done to catch them, they're going to become our adult offenders of tomorrow."
Studies show that one in two sex offenders began their sexually abusive behavior as juveniles.
The rise in juvenile sex offenders has spawned hundreds of new treatment facilities for children as young as 5.