The sexual abuse crisis that engulfed the Roman Catholic Church in the last 12 months has now spread to nearly every American diocese and involves more than 1,200 priests, most of whose careers straddle a sharp divide in church history and seminary training.

These priests are known to have abused more than 4,000 minors over the last six decades, according to an extensive New York Times survey of documented cases of sexual abuse by priests through Dec. 31, 2002.

The survey, the most complete compilation of data on the problem available, contains the names and histories of 1,205 accused priests. It counted 4,268 people who have claimed publicly or in lawsuits to have been abused by priests, though experts say there are surely many more who have remained silent.

The survey provides a statistical framework for viewing the sexual abuse crisis against the modern history of the American Catholic Church. It found, for example, that most priests accused of abuse were ordained between the mid-1950's and the 1970's, a period of upheaval in the church, when men trained in the traditional authoritarian seminary system were sent out to serve in a rapidly changing church and social culture.

Most of the abuse occurred in the 1970's and 1980's, the survey found. The number of priests accused of abuse declined sharply by the 1990's.

But the data show that priests secretly violated vulnerable youth long before the first victims sued the church and went public in 1984 in Louisiana. Some offenses date from the 1930's.

"This has been going on for decades, probably centuries," said Richard K. O'Connor, a former Dominican priest who says he was one of 10 boys sexually assaulted by three priests in a South Bronx parish in 1940, when he was 10. "It's just that all of a sudden, they got caught."

The survey also shows how pervasive the abuse has been. Using information from court records, news reports, church documents and interviews, the survey found accusations of abuses in all but 16 of the 177 Latin Rite dioceses in the United States.

Every region was seriously affected, with 206 accused priests in the West, 246 in the South, 335 in the Midwest and 434 in the Northeast. (Some priests were counted more than once if they abused in more than one region.) The crisis reached not only big cities like Boston and Los Angeles but smaller ones like Louisville, Ky., with 27 priests accused, and St. Cloud, Minn., with 9.

The scandal has set off an intense debate within the church over what caused it and what can resolve it. Many Catholic conservatives blame the reforms of the Second Vatican Council and the social upheaval of the 1960's for removing priestly inhibitions on sexuality and dissent. Liberals tend to find the root causes in what they call the church's repressive approach to sex, including priestly celibacy, and its deeply ingrained culture of secrecy. The Times database provides evidence to support the arguments of both sides.

The data, together with extensive interviews with priests and former priests, abuse victims, church historians, psychologists and experts on sexual disorders, suggest that although the problem involved only a small percentage of priests, it was deeply embedded in the culture of the Catholic priesthood. Many priests began seminary training as young as 13, and all of them spent years being groomed in an insular world in which sexual secrets and transgressions were considered a matter for the confessional, not the criminal courts.

The Times survey counted priests from dioceses and religious orders who had been accused by name of sexually abusing one or more children. It determined that 1.8 percent of all priests ordained from 1950 to 2001 had been accused of abuse.

But the research also suggested that the extent of the problem remains hidden. In dioceses that have divulged what they say are complete lists of abusive priests — under court orders or voluntarily — the percentages are far higher. In Baltimore, an estimated 6.2 percent of priests ordained in the last half-century have been implicated in the abuse of minors. In Manchester, N.H., the percentage is 7.7, and in Boston it is 5.3.

In November, Cardinal Joseph Ratzinger, a top Vatican official, declared that "less than 1 percent" of priests had abused minors, and that there were fewer sex offenders among priests than other groups.

But experts say it is impossible to know whether priests abuse more or less often than people in other professions, or even in the general population, because there are no reliable studies.

The Times data include only cases in which priests were named, and many bishops have released only partial lists of accused priests, or refused to identify any.

"My assessment is it's only the tip of the iceberg," said William R. Stayton, professor and coordinator of the human sexuality doctoral program at Widener University in Chester, Pa., who was shown the results of the Times study. "You really don't have a true picture. I have worked with many clergy sexual abuse cases over the years, and very, very few of them were reported."

That attitude may be changing. Since last January, when the Boston Archdiocese was forced to disclose documents showing that for years its officials had protected priests who molested, hundreds of people have come forward with accusations of abuse.

In those 12 months, as the scandal exploded throughout the church, 432 accused priests have resigned, retired or been removed from ministry.

Because in the nearly 20 years since the problem surfaced the American bishops have refused to cooperate with researchers who sought to initiate studies, the Times study offers the fullest picture possible of the extent of sexual abuse within the church. These are among the other findings:

Half of the priests in the database were accused of molesting more than one minor, and 16 percent are accused of having had five or more victims.

Eighty percent of the priests were accused of molesting boys. The percentage is nearly the opposite for laypeople accused of abuse; their victims are mostly girls.

While the majority of the priests were accused of molesting teenagers only, 43 percent were accused of molesting children 12 and younger. Experts in sexual disorders say the likeliest repeat offenders are those who abuse prepubescent children and boys.

Those ordained in 1970 and 1975 included the highest percentage of priests accused of abuse: 3.3 percent. More known offenders were ordained in the 1970's than in any other decade.

Of the 432 priests removed from or who left the ministry last year, 183 were suspended, living in limbo while waiting for church panels to decide their cases. Bishops were known to have begun the most drastic step, defrocking, for only 11 priests, despite agreeing to a policy at their Dallas meeting last year that encouraged this option. At least nine priests have been reinstated.

The Boston Archdiocese, which received the most scrutiny in news reports last year, did have the most accused priests — 94 — but not the worst problem proportionally. More than a dozen other dioceses had a higher rate of accused priests when taken as a percentage of their active priests.

The study shows only what has become public about a crime usually kept secret by both abuser and victim. Some experts, for instance, contend that the sharp drop in priests accused of abuse in the 1990's is less a result of efforts by the church to confront the problem than a reflection that the victims have not yet come forward.

Resisting Only `Punch and Judy'

The first significant number of priests accused of abuse to emerge in the study were trained in the 1950's and early 1960's. It was the heyday of American Catholicism, when newly comfortable middle-class Catholics financed hundreds of new parochial schools and seminaries, and many of the faith's best and brightest enlisted to serve their church. Many are bishops today.

"The priesthood was riding high," said Jay P. Dolan, a professor of history at the University of Notre Dame and author of "In Search of American Catholicism" (Oxford, 2002). "A lot of boys were entering the seminary. It appealed to your altruism, your desire to help others, and it was a profession very highly valued by Catholics and others."

To qualify, a young man needed little more than to say he felt "called" to a priestly vocation. "Getting in the seminary then was a rather easy process," said Mr. Dolan, who entered a seminary in 1954. "There was no screening of candidates at all. They accepted anybody, and the numbers were incredible."

It was typical then for boys to begin their training in a minor seminary at age 13 or 14, continuing directly through for 10 or 12 years until ordination. Many of the minor seminaries, most of which were phased out starting in the 1970's, were essentially boarding schools. There young men lived together in semi-monastic isolation, missing most of the social, sexual and developmental milestones their peers were experiencing back home.

"If you remained in the system, you were treated the same way when you were 26 as when you were 14 — basically as little children," said the Rev. Robert J. Silva, president of the National Federation of Priests Councils, who studied to be a priest in northern California in the 1950's. "On Thursdays, you signed out to go to town and buy what you needed. You couldn't go to a movie, to a restaurant. You went to a drugstore, and you came home. Once a month when we were younger we used to get what we called a walk into town. We could go and get milkshakes, but we always went together. You rarely socialized with other people."

Seminary instructors warned students to stay away from temptations, but they never mentioned altar boys and teenagers. Their chief concerns, Mr. Dolan remembers, were "Punch and Judy" — alcohol and women.

Diocesan priests take a vow of celibacy, promising never to marry or have sex with women. Seminarians were taught that all other sexual activity was unchaste and sinful, but not a violation of the celibacy vow.

Some priests relied on this distinction to rationalize to their victims, the authorities or church superiors that mutual masturbation, fellatio or touching children's bodies, however wrong, left their celibacy vow intact, according to some victims, therapists who treated the abusers and court records.

In general, though, the entire subject of sexuality was taboo in seminaries.

"It amounted to don't ask, don't tell, don't touch," said Paul E. Dinter, a former priest ordained in 1965 and the author of a new book, "The Other Side of the Altar" (Farrar Straus & Giroux). "In my lifetime there were still seminaries handing out paddles so you could tuck your shirt into your pants and never touch yourself. There were nuns showering in gowns so they were never naked."

Psychologists who have treated priest offenders now say that such a sexually repressed environment appealed to some young men who felt guilty about being sexually stimulated by children, male teenagers or adult men.

Dr. Eli Coleman, professor and director of the Program in Human Sexuality at the University of Minnesota Medical School, said, "The church was definitely an attractive haven for a lot of people who naturally wished that somehow, through a spiritual life, they would not have to deal with those conflicts."

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