The study, funded by the U.S. Department of Justice, found that the percentage of children who reported being physically bullied over the past year had declined from nearly 22 percent in 2003 to under 15 percent in 2008. The percentage reporting they'd been assaulted by other youths, including their siblings, dropped from 45 percent to 38.4 percent.
The lead author of the study, Professor David Finkelhor, said he was "very encouraged."
"Bullying is the foundation on which a lot of subsequent aggressive behavior gets built," said Finkelhor, director of the University of New Hampshire's Crimes Against Children Research Center. "If it's going down, we will reap benefits in the futurein the form of lower rates of violent crime and spousal assault."
Finkelhor noted that anti-bullying programs had proliferated and received funding boosts following the 1999 Columbine High School shootings in Colorado.
"There is evidence these programs are effective," he said. "I wouldn't be surprised if we're seeing the fruits of that."
One of the largest of these initiatives is the Olweus Bullying Prevention Program, which has been implemented in several thousand U.S. schools. It is a comprehensive program that includes forming an anti-bullying committee, training staff to intervene immediately if they observe bullying and meeting with students and parents when problems occur.
Marlene Snyder, of Clemson University's Institute on Family and Neighborhood Life, who is director of development for Olweus, said the survey was heartening to those in the anti-bullying field but not cause for complacency.
"The decline is not happening everywhere," she said. "It's in schools where adults really understand how detrimental this conduct can be and have made a conscious effort to bring these numbers down."
The findings by Finkelhor and his co-authors were based on two national surveys of children ages 2 to 17 conducted five years apart - the first in 2003, involving 2,030 children, and the second in 2008, asking the same questions of 4,046 children. The findings were published this week in the Archives of Pediatrics & Adolescent Medicine.
Children aged 10-17 were interviewed directly about various forms of violence and victimization they had experienced. In the cases of children under 10, parents or other caregivers were interviewed.
The researchers said the biggest declines in the various forms of violence and bullying were among children from low-income households.
Snyder said this finding meshed with observations by the Olweus staff.
"Many of the grants have been awarded to large inner-city schools where crime and violence rates had been high and economic conditions were low," she said. "We've seen that when those communities have had the money, they could be successful."
Snyder cautioned that even schools making headway against bullying programs should remain vigilant.
"You have to keep at it, training new teachers every year - not just training one time and you're done," she said. "I hope this progress holds because, frankly, when they have to make hard decisions, these are the kind of programs that often fall under the financial ax."
Diane Cargile, president of the National Association of Elementary School Principals, said she was pleased but not surprised by the survey's findings.
"I know the efforts that principals and teachers have made to be sure they have a safe school - from the ride on the bus in the morning, through the day at school, to the ride home," said
Cargile, principal at Rio Grande Elementary School in Terre Haute, Ind.
She said the anti-bullying initiatives have made many children more willing to seek help from adults when they are targeted.
Along with bullying and assaults by peers or siblings, the new study also found declines in several other forms of child victimization, including sexual assaults and emotional abuse by caregivers. It found slight increases in dating violence, robbery targeting children and the witnessing of violence among other family members.
The survey did not specifically address the bullying of young people for reasons related to sexual orientation, which gay-rights groups consider to be a pervasive problem. The Gay, Lesbian and Straight Education Network said its research indicates this type of harassment remained stable between 2001 and 2007.
Overall, the findings by Finkelhor and his co-authors were positive - and came on the heels of a major federal study documenting an unprecedented decrease in incidents of serious child abuse. That report, the National Incidence Study of Child Abuse and Neglect, found that incidents of serious physical, sexual or emotional abuse dropped by 26 percent from 1993 to 2005-06.
Professor James Garbarino, an expert on childhood aggression at Loyola University's Center for the Human Rights of Children in Chicago, drew an analogy between the campaign against bullying and efforts that began even earlier to combat domestic violence.
"If you pay attention to a phenomenon and devote some resources to dealing with it, praise the Lord, sometimes we actually improve things," he said. "It's gotten on people's radar. There have been more and more challenges to the myths that bullying can be good for kids, that it builds strength."Read more Parenting Perspective blogs by visiting the Parenting Channel on 6abc.com.