Harriet Stratemeyer Adams, author of 60 Nancy Drew mysteries and more than 100 other children's novels, was the Henry Luce of juvenile publishing.

For 52 years, until her death Saturday at the age of 89, she presided over the Stratemeyer Syndicate, a fiction empire including dozens of popular series--among them Tom Swift, the Hardy Boys, the Bobbsey Twins and the Rover Boys--which have sold more than 250 million copies. And she shaped the imaginations of countless millions of American children through books whose gee-whiz appeal our cynical age cannot stale nor changing customs wither.

"She probably had more to do with young people getting into the habit of reading than anyone else," said Jack Artenstein, publisher of Simon & Schuster's juvenile group, which has published 3 million copies of some 50 Stratemeyer titles since 1979, including Nancy Drew. "Even TV couldn't hurt the sales of the books," Artenstein said yesterday from New York. "The series is stronger than ever before."

Adams was the senior partner in the syndicate, founded in 1906 by her father, Edward Stratemeyer. An ingenious and awesomely prolific man, Stratemeyer created more than 100 different series, writing many himself and, in later years, outlining the plots and contracting the writing to others. During the last year of his life he wrote the first three volumes of a new series, Nancy Drew, which also embodied what Nancy Axelrad, one of the three remaining syndicate partners, calls "the famous Stratemeyer formula."

"The basic emphasis was on adventure and excitement," each chapter had to "build up to a high point or suspenseful note," and "the first page was always the most important." In the latter category, Stratemeyer's standards were painfully exacting. He often asked his writers for as many as 20 rewrites of the first page, and once struck out an author's entire opening, substituting instead the single word, "Bang!"

Following his death in 1930, Adams and her sister formed a partnership to continue their father's work. The output of the Maplewood, N.J., firm would ultimately grow to 1,200 titles, many of which Adams wrote under pseudonyms. She had little previous experience, having spent only a year with the syndicate following her graduation from Wellesley in 1914, before marrying and settling in Maplewood. But soon she was turning out passages like this, from "The Message in the Hollow Oak" (1935):

"It's a ghost," Bess insisted, her teeth chattering with fright.

"There are no ghosts," Nancy returned firmly. But it took all her courage to add, "I'm going down to the cellar to find out just what it really is!"

As the list of books grew (and were translated into a dozen languages), "she used to say that Nancy Drew was her fictional daughter," said Axelrad, and would spare no expense in traveling to research the volumes. Axelrad, who writes the Bobbsey Twins and other books now, along with half a dozen contract writers, said yesterday from New Jersey that the syndicate is still turning out the Hardy Boys, Bobbsey Twins and Tom Swift series ("now set in an undated future") as well as two Nancy Drew volumes a year, with few changes from the original formula. As the decades passed, "we became very sensitive to the concerns of minority groups," she said, and Adams oversaw the revision of "the Bobbsey Twins' earlier titles, which tended to depict stereotypes about blacks."

"There's a trend today toward more realistic material in children's books," said Axelrad, but Adams kept Nancy Drew inviolate. "She has quit wearing her cloche hat and white gloves," and as for the old blue roadster, "she traded it in several times." And even if, in this age of loose libidos, "Nice Girls Do," Nancy doesn't. Her "longstanding relationship with Ned Nickerson," maintained with Adams' unremitting scrupulosity, will continue, said Axelrad. "If they got married, that would be the end of the series."

Nancy Drew may be immutable, but Adams, "despite her age, was always willing to make a change," said Axelrad. In 1979, after the syndicate found itself in a royalty dispute with its publisher, Grosset & Dunlap, Stratemeyer asked Simon & Schuster to take over its line, precipitating a lengthy lawsuit. Grosset now publishes the pre-1979 hard-cover titles, and Simon & Schuster the rest. Adams would personally approve the book covers, Artenstein recalled, checking to see if Nancy Drew and other characters had been depicted "appropriately." "Sometimes an artist would have some of Nancy Drew's hair out of place," and Adams would become "very forceful" about correcting it, said Artenstein, who called Adams "very, very sharp" about business details.

But "I've dealt with many authors and agents through the years," he said, "and dealing with her was really rare. You never had to question her sincerity, and she was totally above-board, honest, direct and kind."