The amount of violence committed by teenagers -- both in and out of school -- has declined significantly since the early 1990s, according to a study whose findings run counter to the widespread public impression of escalating juvenile violence.

A biennial survey by the Centers for Disease Control and Prevention showed sharp decreases in several categories of violent activity by teenagers -- such as carrying a weapon or fighting -- between 1991 and 1997, the most recent year for which data is available. In other categories -- such as being threatened with a weapon or having property stolen -- the survey found no appreciable change.

"None of the behaviors we studied showed any sign of going up," said Thomas R. Simon, co-author of the study, which surveyed 16,000 students in grades 9 through 12 and was published in today's edition of the Journal of the American Medical Association.

That overall finding clashes with a public perception of teenagers as increasingly dangerous, a view driven in part by a series of high-profile school shootings over the past two years. That view has pressured lawmakers and prosecutors to crack down on juvenile offenders, often by trying more of them as adults. After the April shooting at Columbine High School in Littleton, Colo., for example, the House and Senate rushed to pass long-delayed juvenile justice bills.

Nonetheless, for several years, Justice Department reports have shown decreases in crime committed by youth. The CDC study extends that good news to violent behaviors that do not reach the attention of the criminal justice system.

The most dramatic drops recorded in the study involved teenagers carrying guns and other weapons. About 18 percent of the those surveyed in 1997 reported carrying a weapon -- defined as a gun, knife or club -- in the previous month, down from 26 percent in 1991. About 9 percent admitting carrying a weapon at school during the same period, down from almost 12 percent in 1993 -- the first year that question was asked.

The frequency of fighting also declined, though less precipitously. Of those teenagers surveyed in 1997, 37 percent reported being in a physical fight in the previous year, down from 43 percent in 1991. Students injured in fights seriously enough to need medical attention also declined to below 4 percent, a decline of nearly a percentage point.

There was no statistically significant decrease, however, in the 12 percent of teenagers surveyed who had carried a weapon other than a gun in the previous month. Similarly, there was no change in the proportion who said they had skipped school in the previous month because they felt unsafe (4 percent), who were threatened or injured by a weapon at school (7 percent) or who had their property stolen or damaged at school (33 percent).

The study's authors did not offer their own reasons for the decline in so many categories of youth violence, but cited other research that has focused on the nation's prospering economy, ebbing warfare between gangs that deal in crack cocaine, the shift to community policing, adoption of tougher school discipline policies and an expansion of violence prevention programs. "It's likely we're seeing a payoff," Simon suggested.

Jack Levin, a sociology professor who directs the Brudnick Center on Violence at Northeastern University, emphasized the impact of broad police-community partnerships formed in recent years to attack the problem in many big cities, where juvenile crime has been more prevalent than in suburbs or rural areas. He pointed to a model community partnership that Boston formed in 1992 after clergy were outraged by gang members stabbing rivals at a funeral. Levin said the partnership has led to local business leaders generating 11,000 summer jobs, more college students tutoring in the schools, parents volunteering to supervise after-school programs and ministers providing spiritual guidance to gang members.

"For 25 years, we asked our teenagers to raise themselves, and they didn't do a very good job of it," Levin said. "That's why [youth violence has] gone down -- the adults are back."

Pamela L. Riley, executive director of the Center for the Prevention of School Violence based in Raleigh, N.C., emphasized the role of anti-violence policies in the schools, noting the increasing number of police officers assigned to schools and a 1995 anti-crime law that forced schools, in exchange for federal aid, to expel for a year any student caught with a gun. Under that law, 6,100 students were expelled in the 1997-1998 school year.

Despite the encouraging trends, the CDC study warns that "the prevalence of youth violence and school violence is still unacceptably high."

Further breakdowns of the survey results highlighted a few areas of ongoing concern. For example, the study found declining participation in fisticuffs by black and white students, but no such decline among Hispanic students. Both boys and girls were fighting less, but the decrease was sharper among girls. And compared to whites, more blacks and Hispanics were involved in fights.

Countering Stereotypes

Percentage of hich school students who engaged in the following violence-related behaviors:

Carried a weapon

`91 26.1

`97 19.3

Carried a weapon on school property

`91 N/A

`93 11.8

`97 8.5

Carried a gun

`91 N/A

`93 7.9

`97 5.9

In a physical fight

`91 42.5

`97 36.6

In a physical fight on school property

`91 N/A

`93 16.2

`97 14.8

Injured in a physical fight

`91 4.4

`97 3.5

SOURCE: Journal of the American Medical Association