For 20 years, Iain Calder ran the National Enquirer, one of the top-selling publications in the United States. The former tabloid editor says the paper started a trend that, for better or worse, changed the face of American journalism.

It is called a tabloid, a newspaper just half the size of a conventional daily. But the National Enquirer is distinguished from its more sober, full-sized counterparts by its blaring headlines and sensational stories, often about celebrities and their foibles.

Iain Calder mastered the skills he would use to run the Enquirer in his native Scotland, where editors were ruthless and young reporters had to be resourceful. He says a circulation war in Glasgow shaped his take-no-prisoners style of reporting.

"That's really where I learned to be tough and to find ways to get stories, because you couldn't go back and tell your boss 'I can't get the story' or 'Someone beat me.' It was a wild, wild, wild, wild time," Mr. Calder says.

The experience would prepare him for an upstart U.S. tabloid called the National Enquirer. At 25, Mr. Calder became the paper's European bureau chief.

He admits the paper was something an embarrassment in those early days, even by the garish standards of the British tabloids. The Enquirer was filled with gory pictures of headless corpses and charred murder victims.

But changes were in the offing that would boost the paper's circulation to five million copies.

Mr. Calder says longtime Enquirer publisher Gene Pope was a marketing genius with a knack for gauging the interests of his readers. Mr. Pope eliminated much of the blood and gore and focused on celebrities, mostly those from television, who were ignored by the popular movie magazines.

The publisher also placed his newspaper near the checkout stands of supermarkets, enticing shoppers to pick up a copy as they waited to pay for their groceries. Before long, the weekly paper far outsold all the major dailies.

Over the years, the National Enquirer has had its share of journalistic coups. Democratic presidential candidate Gary Hart saw his political fortunes plummet in 1987 when the Enquirer published a picture of the married candidate on a boat called Monkey Business with a woman named Donna Rice sitting on his lap.

Mr. Calder says the Enquirer scooped other papers when it photographed former baseball star Pete Rose inside a federal prison where he was serving a five-month sentence for filing false tax returns. Two Enquirer reporters got into the prison in Marion, Illinois, by posing as musicians who had come to give a concert.

The paper also uncovered evidence in the O.J. Simpson murder trial, persuading a clerk to admit, with a $17,000 payment, he had sold the former football star a knife.

Known for "checkbook journalism," Mr. Calder says the Enquirer pays well for tips from friends and confidantes of celebrities.

But are the stories true? Critics assume they are not, but Mr. Calder says Enquirer readers know better.

"The answer absolutely, unequivocally is, yes, it had to be true to be in the Enquirer," Mr. Calder says. ?Now, did we ever make a mistake? Absolutely. There's no journalist or no paper in the world that can say they never made a mistake. The New York Times just had an editor fired because of a string of phony stories. The Washington Post gave back a Pulitzer Prize when [reporter] Janet Cook admitted that she had made up people wholesale to do a story for the Washington Post".

One publicized mistake by the National Enquirer led to a rare apology when the paper lost a libel lawsuit to comedian Carol Burnett after a story suggested she was drinking too much and was rowdy at a celebrity gathering.

But the editor says that if truth were not a concern, the paper could have saved a fortune by making up its stories instead of paying thousands for tips from informants.

He says American journalists take themselves seriously, viewing their role as protectors of cherished freedoms. As a result, he says, their stories are often boring.

"I would be criticized by other American journalists who said, you're pandering to readers," Mr. Calder says. ?My answer to that was, do you believe in democracy? And they said, of course I believe in democracy. And I said, well, if the American public is smart enough and wise enough and discerning enough to vote for president of the United States, are they not wise and discerning enough to vote for a newspaper that they like?"

The former editor says, for better or worse, the National Enquirer has helped change news reporting in the United States. Even his harshest critics agree with the statement. The media obsession with celebrity, magazines like People and Us, television shows like Entertainment Tonight and new entertainment networks were all inspired in part by the success of the Enquirer.

An unrepentant Iain Calder looks back at his days on the paper with some fondness. He says he oversaw a team of crack reporters who were among the most resourceful in the business.

"It was a wonderful thing to come into the office every day not knowing what was going to happen, but knowing I had the equivalent of the Green Berets ready to go to war for me. It was a wonderful feeling," Mr. Calder says.

Iain Calder's book, The Untold Story: My 20 Years Running the National Enquirer, is published by Miramax Books. Unlike the Enquirer, it cannot be found in supermarkets, but in bookstores.