Anyone reading the headlines in recent weeks has come away with an unsettling message: Sexual predators seem to lurk everywhere.

In a single day last week, juries deliberating 200 miles apart in Pennsylvania delivered guilty verdicts against Jerry Sandusky, a former assistant football coach at Penn State, for sexually molesting boys, and against Monsignor William J. Lynn, a clergy secretary, for shielding predatory priests. In New York, accusations of sexual abuse at Horace Mann, an exclusive preparatory school, recently spurred two law enforcement agencies to open hotlines and an 88-year-old former teacher at the school to admit to having had sexual interactions with students decades ago.

To child abuse advocates and criminal justice experts, such cases suggest that efforts to raise awareness about sexual abuse and its emotional consequences have been effective. The public, they say, is finally willing to believe victims, even when the abuse took place years in the past, and to hold institutions responsible for failing to take action.

“We’re at a bit of a watershed moment,” said Teresa Huizar, executive director of the National Children’s Alliance, a nonprofit organization devoted to preventing child abuse that provides support and training to more than 750 child advocacy centers across the country.

But if the convictions of Sandusky and Lynn represent a success story, the furor surrounding them tends to obscure what may be an even more significant achievement, albeit one that receives little publicity: The rates of child sexual abuse in the United States, while still significant and troubling, have been decreasing steadily over the past two decades by several critical measures.

Overall cases of child sexual abuse fell more than 60 percent from 1992 to 2010, according to David Finkelhor, a leading expert on sexual abuse who, with a colleague, Lisa Jones, has tracked the trend. The evidence for this decline comes from a variety of indicators, including national surveys of child abuse and crime victimization, crime statistics compiled by the FBI, analyses of data from the National Data Archive on Child Abuse and Neglect and annual surveys of grade school students in Minnesota, all pointing in the same direction.

From 1990 to 2010, for example, substantiated cases of sexual abuse dropped from 23 per 10,000 children younger than 18 to 8.6 per 10,000, a 62 percent decrease, with a 3 percent drop from 2009 to 2010, according to the researchers’ analysis of government data. The Minnesota Student Survey charted a 29 percent decline in reports of sexual abuse by an adult who was not a family member from 1992 to 2010 and a 28 percent drop in reports of sexual abuse by a family member. The majority of sexual abuse cases involve family members or acquaintances rather than strangers, studies have found.

At the same time, the willingness of children to report sexual abuse has increased. In a 2008 survey, Finkelhor, director of the Crimes Against Children Research Center at the University of New Hampshire, found that in 50 percent of sexual abuse cases, the child’s victimization had been reported to an authority, compared with 25 percent in 1992.

The precise reasons for the declining rates are not clear. Finkelhor noted that most types of crime have plummeted over the past 20 years. But at least some of the decline, he believes, has resulted from greater public awareness, stepped-up prevention efforts, better training and education, specialized policing, the presence in many cities of child advocacy centers that offer a coordinated response to abuse, and the deterrence afforded by the prosecutions of offenders.

“Also, I think we live in a society with much more surveillance than was true in the past,” Finkelhor said. “It’s not just that people have gotten prosecuted for it but in general people’s sense that everybody’s private stuff is much more likely to be revealed.”

His findings initially met with resistance, especially from advocates and treatment professionals, who said they saw no reduction in the number of victimized children who needed their help.

Although the decline is now widely accepted among researchers and many advocates, some are still skeptical. Asked about the downward trend at a congressional hearing in May, Michael Johnson, youth protection director for the Boy Scouts of America, said, “It always bothers me any time I hear these statistics about abuse and neglect.”

In some groups, like American Indians, he said, sexual abuse is still pervasive. And the Internet has added to the problem, making it easier for predators to find victims, he continued.

“The incidences are higher and it’s more threatening,” he said.

Dr. John M. Leventhal, a professor of pediatrics and the director of the child abuse program at Yale New Haven Children’s Hospital, says that the number of cases his clinic sees has gone down, from more than 400 a year to about 350. He does not dispute a decline, but he suggested that changes in how child protection agencies classify cases could be contributing to the decrease.

Finkelhor, however, said those changes took place after the biggest declines in the 1990s.

Mark Chaffin, a professor in the department of pediatrics at the University of Oklahoma Health Sciences Center, had one possible explanation for why it was hard for some people to accept the numbers.

“The child abuse field has always been one that felt like there was not enough public policy attention, so the narrative reflected that. It’s at crisis proportions; it’s getting worse every year; it’s an epidemic,” he said. “So when people hear that the rates are going down, it really is sort of a challenge.”

Lucy Berliner, director of the Harborview Center for Sexual Assault and Traumatic Stress in Seattle, notes that many child advocacy groups depend on government financing, and good news always brings mixed feelings. One of them is the fear that if the issue does not seem dire enough, the money might dry up.

“It is very risky to suggest that the problem you’re involved with has gotten smaller,” she said.

Yet she and others in the field have embraced the decline as evidence that their work has made a difference.

“What we’ve arrived at is celebrating the success and using that to argue that the investments that government has made has been very worthwhile,” Berliner said.

The effectiveness of those investments, said Marci A. Hamilton, a constitutional law professor and an advocate for children at Benjamin N. Cardozo School of Law, is evident, and can be seen in the trials in Pennsylvania.

“I think there’s more of a willingness of victims to come forward and more willingness of the support system of the victims to let them come forward,” she said.

“There was a time when if a victim came out, the universal response around them was, ‘You’ll get over it. Thank you for telling me but let’s move on,”’ Hamilton said. “The more public education you have about the consequences, the more willing spouses and parents are to say, first, I believe you; and, second, you need therapy because we all know that this has lifelong dangerous effects.”

© 2012 The New York Times Company