It took decades for American society to heed the tales of sexual violation told by its children.

One of the country's last taboos was lured into the open by psychologists, television producers, federal bureaucrats, police, social workers, writers, elected officials and others on a spectrum ranging from sexual reformers to the late FBI Director J. Edgar Hoover, from liberal former senator Walter F. Mondale (D-Minn.) to conservative Sen. Paula Hawkins (R-Fla.).

Just as their efforts are beginning to pay off in public attention and policy, however, the issue is in danger of again sliding away. As cases pass through a criminal justice system ill-suited to handle them and confused children change their stories, professionals on the issue say they fear a backlash.

"Just as people were starting to feel that, yes, it's really a problem, now they hear of a child 'lying' in Jordan, Minn., or changing his story in California, and they're saying, 'Whew, it's not such a problem after all,' " said Anne Cohn, director of the National Committee for the Prevention of Child Abuse in Chicago.

Public focus on sex crimes against the young coalesced with unusual speed, experts say, provoking what some call hysteria.

At the same time, said Kenneth Lanning, the FBI's foremost specialist on sex crimes against children, the most common reaction is "denial. People just do not want to think about this, especially when you're talking about 'nice people,' about ministers, priests and teachers, day-care workers and scoutmasters . . . . If you're talking about weird sickoes, yeah, people will get all cranked up about that."

Some specialists blame Sigmund Freud, credited as the founder of psychoanalysis, for society's long denial of the problem. His theories of childhood sexuality broke the taboo against its mention, but he later declared that female patients' stories of incest were fantasies. The loosening of Victorian moralism and society's growing attentiveness to the plight of the vulnerable opened the door; a coalition of the feminist and child-protection movements forced the specter out of the closet.

Statistical clues have been available for decades. Alfred C. Kinsey, in a 1953 study of sexuality, found that about 28 percent of the women he interviewed had been molested as children.

But David Finkelhor of the Family Violence Research Program at the University of New Hampshire says that Kinsey and other sexual reformers of the time didn't push the issue because they were locked in combat with "antisexuality" groups, who counted FBI chief Hoover among their champions.

"Kinsey and the others didn't want to feed into the alarms of the conservative antisexuality people" by focusing on child abuse, he said. Eventually, as many reforms were adopted, reformers no longer felt so defensive, and as the feminist movement gained strength, women began to see that certain issues were "being swept under the table," according to Finkelhor.

Experts know that the problem is not new, in part because most studies of it focus on adults who were molested as children. "Among adults molested as children we are finding that often their parents were molested as children, and sometimes their grandparents, and so on," said Terri Muessig, a spokesman for Parents United in San Jose, which treats incest victims and offenders.

Studies indicate that between 1 in 3 and 1 in 6 American women were sexually victimized during childhood by an adult. The estimate for men is 1 in 10 to 1 in 20.

The current rash of highly publicized cases at day-care centers is not typical, professionals caution. It is estimated that more than half of all cases take place within the supposed sanctuary of home and family, usually in the form of father-daughter incest. About 85 percent involve a parent, other relative or trusted acquaintance; only a small fraction are committed by the stereotypical molester -- such as the stranger at the playground.

Among factors that focused attention on the issue:

* In 1971, psychologist Dr. Henry (Hank) Giarretto developed a pilot program for San Jose's juvenile probation department, which was seeing a trickle of families with instances of incest. The result was Parents United, which became a model for dealing with incest cases -- by treating whole families, and by bringing offenders together with other offenders, victims with other victims, for group therapy and support, and working with law enforcement authorities.

* In l973, then-Sen. Mondale headed the first congressional hearing on physical abuse of children. Those hearings led to legislation that created, in what was then the Department of Health, Education and Welfare, an agency called the National Center on Child Abuse and Neglect (NACAM). It helped set up procedures to encourage the reporting of abuse, and gave grants that encouraged professional groups to revise the system's response.

* In the mid-1970s, officers of the Los Angeles Police Department (LAPD) began to see the results of the sexual reformers' challenges to antipornography laws: much more explicit pornography. The result was a pilot project funded by the city in the summer of 1977 setting up the LAPD's eight-member Sexually Exploited Children Unit, the oldest and largest such unit in the country.

* In 1978, with the passage of legislation authored by Rep. George Miller (D-Calif.), Congress for the first time recognized sexual abuse of children as a special, separate concern. The Child Protection Act of 1978 clarified laws on child pornography and helped trigger FBI involvement.

Thus, the climate was ripe on January 9, 1984, when 60 million people watched a movie called "Something About Amelia" on ABC TV, in which a handsome, successful family man molests his daughter. Child-abuse specialists call it a "singular, major event" in unleashing confessions by the abused and even by abusers.

Thereafter, a succession of dramatic multiple-abuse cases began to make the headlines, and last April, Sen. Hawkins, at a hearing of the Senate Children's Caucus, disclosed that as a kindergartner, 50 years earlier, she had been sexually abused by an elderly neighbor.

The American Humane Association estimates that 71,961 children were reported sexually abused in 1983, the last year for which statistics are available. That would represent an increase of 852 percent over 1976 in reported cases. One in four involved children under age 5.

But with the media blitz and public attention has come much confusion.

"The mood has changed," said Detective Ralph W. Bennett, head of the LAPD's child sexual-abuse unit. "I think it's become something of a hysteria, or a paranoia . . . . There are child-care workers who are absolutely petrified of being accused of being a child molester," he said, and parents ready to charge that their children have been molested based on the slimmest evidence.

"We progressed from a situation where the common thing was to say we can't believe children, they fantasize these things, to where the standard line became children don't lie . . . not on sexual things," said the FBI's Lanning.

Experts generally say that children seldom lie about such matters, but that they don't necessarily tell the whole truth. They may misunderstand, or be "led" by an incompetent questioner. They may be intimidated by family members or by skillful defense attorneys. In cases where many children have been abused, they may be influenced by talking to each other.

Child molesters are difficult to convict even if they are guilty and authorities make no mistakes, experts point out.

They say the solution lies in using common sense and caution, in better training for professionals at every level, and in adjustments in courtroom procedures to accommodate children while maintaining the rights of the accused.

"The most unfortunate thing," Lanning said, "would be if everybody goes back to the way we were before."