BESTSELLING AUTHOR J.K. ROWLING IS STILL TRYING TO FATHOM THE INSTANT FAME THAT CAME WITH HER FIRST CHILDREN'S NOVEL.

I must confess to a certain bias: I grew up in a dilapidated old farmhouse in County Wicklow, Ireland, a place with a rainy magic not unlike the witch family's cozy but crumbling home in the second of J.K. Rowling's "Harry Potter" books. I am also a terminal Anglophiliac, partial to lisps and knee socks. So when my all-American techno-savvy twin boys abandoned their nihilistic computer games to read about groundskeepers, goblins, prefects and tea sausages, I was delighted.

As befits stories about magical powers, the popularity of Rowling's debut novel, "Harry Potter and the Sorcerer's Stone" (published in Great Britain under the title "Harry Potter and the Philosopher's Stone"), is a little unconventional itself -- a fire built kid by kid, fanned by whispers in classrooms on both sides of the Atlantic. Which makes it all the more phenomenal that the book, aimed at 8- to 12-year-olds, is currently enjoying its 15th week on the New York Times Bestsellers list. (By contrast, the last major "crossover" novel, Philip Pullman's 1996 book "The Golden Compass," was marketed as such by Knopf in an expensive campaign that made it a huge seller, though it did not make the Times list.)

A fresh, clear spring of thrilling narrative, "Harry Potter" is also No. 1 on the Independent Booksellers List, pulling ahead of John Grisham's "The Testament." It's no wonder that in Britain, Rowling's children's books come in two jacket designs -- one aimed at children and one plain enough that adults can read the books in public.

In the next book of the series, "Harry Potter and the Chamber of Secrets," Rowling expands the fascinating world of Hogwarts School of Witchcraft and Wizardry with surprises around every turn: a diary that writes back; ancestral portraits that primp and curl their hair at night; a behemoth groundskeeper with a soft spot for man-eating pets; a professor who died, didn't notice and continued teaching as a ghost. At one point, Harry is warned that some books are dangerous: "Some old witch in Bath had a book that you could never stop reading! You just had to wander around with your nose in it, trying to do everything one-handed!"

Rowling has written another such book. Word-of-mouth publicity on the sequel has already been so strong that its American publisher, Scholastic, has announced that it is moving up the U.S. release date from September to June.

Clearly the publisher felt pressured by loyal Potterites who had already begun purchasing copies online or smuggling them in from the United Kingdom, where it was released last July. Executive Vice President Barbara Marcus also said Scholastic plans to schedule the release dates for the rest of the series closer to British publication dates "for obvious reasons."

The story of Harry Potter's creator, Joanne Rowling, is itself somewhat magical: She was impoverished and raising her baby daughter alone while finishing the first "Harry Potter" story; a grant from the Scottish Arts Council enabled her to finish it. (Knowing this makes you cheer all the louder when Harry himself escapes the spiritual poverty of his cruel aunt and uncle to board the train for Hogwarts School and its realm of infinite possibility and rich, if odd, traditions.) Salon reached Rowling in her home in Edinburgh, Scotland, where she talked about instant fame, the "muggle" and single motherhood.

The advertising copy for your book says that you were a struggling single mother when writing "Harry Potter and the Sorcerer's Stone." Could you tell more about that time?

In fact, I wasn't a struggling single mother all the time that I was writing the first "Harry" book. It was only during the final year of writing that I found myself poorer than I'd ever been before. Obviously, continuing to write was a bit of a logistical problem: I had to make full use of all the time that my then-baby daughter slept. This meant writing in the evenings and during nap times.

I used to put her into the pushchair and walk her around Edinburgh, wait until she nodded off and then hurry to a cafe and write as fast as I could. It's amazing how much you can get done when you know you have very limited time. I've probably never been as productive since, if you judge by words per hour.

What was it like when you realized the book was a success?

It sounds a bit twee, but nothing since has matched the moment when I actually realized that "Harry" was going to be published. That was the realization of my life's ambition -- to be a published author -- and the culmination of so much effort on my part. The mere fact that I would see my book on a bookshelf in a bookshop made me happier than I can say.

I had been very realistic about the likelihood of making a living out of writing children's books -- I knew it was exceptionally rare for anybody to do it -- and that didn't worry me. I prayed that I would make just enough money to justify continuing to write, because I am supporting my daughter single-handedly. I was hoping I would be able to teach part-time (by this time I was working as a French teacher) and still write a bit.

Three months after British publication, my agent called me at about eight one evening to tell me there was an auction going on in New York for the book. They were up to five figures. I went cold with shock. By the time he called back at 10 p.m., it was up to six figures. At 11 p.m., my American editor, Arthur Levine, called me. The first words he said to me were: "Don't panic." He really knew what I was going through. I went to bed and couldn't sleep. On one level I was obviously delighted, but most of me froze.

For the first time ever in my life, I got writer's block. The stakes seemed to have gone up a lot, and I attracted a lot of publicity in Britain for which I was utterly unprepared. Never in my wildest imaginings had I pictured my face in the papers -- particularly captioned, as they almost all were, with the words "penniless single mother." It is hard to be defined by the most difficult part of your life. But that aspect of the story is, thankfully, receding a little in Britain; the books are now the story, which suits me fine.

In your books, Hogwarts School is incredibly fantastic, from its forbidden forest and Quidditch fields and endless castle dungeons to its talking portraits and Harry's own snug four-poster bed. Do you see school as a potential sanctuary for children?

I'm often asked whether I went to boarding school and the answer is "no." I went to a "comprehensive" -- a state-run day school. I had no desire whatsoever to go to boarding school (though if it had been Hogwarts, I would have been packed in a moment). School can be a sanctuary for children, but it can also be a scary place; children can be exceptionally cruel to each other.

In this era of very involved parenting, do you think that the notion of boarding school and the autonomy it offers might hold an almost taboo allure for both kids and parents?

I think that's definitely true. Harry's status as orphan gives him a freedom other children can only dream about (guiltily, of course). No child wants to lose their parents, yet the idea of being removed from the expectations of parents is alluring. The orphan in literature is freed from the obligation to satisfy his/her parents, and from the inevitable realization that his/her parents are flawed human beings. There is something liberating, too, about being transported into the kind of surrogate family which boarding school represents, where the relationships are less intense and the boundaries perhaps more clearly defined.

Did any characters or scenes in "Harry Potter" stem from your experience as a single mother?

So much of "Harry Potter and the Sorcerer's Stone" was written and planned before I found myself a single mother that I don't think my experiences at that time directly influenced the plot or characters. I think the only event in my own life that changed the direction of "Harry Potter" was the death of my mother. I only fully realized upon re-reading the book how many of my own feelings about losing my mother I had given Harry.

In your first book, the witches and wizards stand out as slightly odd when they're in the "muggle," or normal world -- cloaked in capes with dozens of pockets. Are they meant to remind readers of homeless people?

Not necessarily of homeless people, although that image isn't far off what I was trying to suggest. The wizards represent all that the true "muggle" most fears: They are plainly outcasts and comfortable with being so. Nothing is more unnerving to the truly conventional than the unashamed misfit!

Did your teaching experience help you write for children?

I taught for about four years, mainly teenagers. It is my own memories of childhood that inform my writing, however; I think I have very vivid recall of what it felt like to be 11 years old. The classics part of my degree at Exeter College did furnish me with a lot of good names for characters -- not exactly the use my lecturers expected me to put it to, however.

One of the book's loveliest characters is Hermione Granger, one of Harry's best friends and a bookworm whose research invariably helps him unravel the mystery at hand. Hermione makes erudition seem so juicy and worthwhile, yet she's very real, prone to crushes on self-inflated types. How did you dream her up?

Hermione was very easy to create because she is based almost entirely on myself at the age of 11. She is really a caricature of me. I wasn't as clever as she is, nor do I think I was quite such a know-it-all, though former classmates might disagree. Like Hermione, I was obsessed with achieving academically, but this masked a huge insecurity. I think it is very common for plain young girls to feel this way. Similarly, her crushes on unsuitable men ... well, I've made my mistakes in that area. Just because you've got a good brain doesn't mean you're any better than the next person at keeping your hormones under control!

What were the most memorable books you read as a child?

My favorite book when I was younger was "The Little White Horse" by Elizabeth Goudge. My mother gave me a copy when I was 8; it had been one of her childhood favorites. I also loved "Manxmouse" by Paul Gallico and, of course, C.S. Lewis' Narnia books.

In both Harry Potter books, your vocabulary is extraordinarily rich and inventive. How does one encourage children to cultivate a bank of words like this?

I always advise children who ask me for tips on being a writer to read as much as they possibly can. Jane Austen gave a young friend the same advice, so I'm in good company there.

Do you think the English language is more alive in Great Britain than in the United States?

Part of what makes a language "alive" is its constant evolution. I would hate to think Britain would ever emulate France, where they actually have a learned faculty whose job it is to attempt to prevent the incursion of foreign words into the language. I love editing "Harry" with Arthur Levine, my American editor -- the differences between "British English" (of which there must be at least 200 versions) and "American English" (ditto!) are a source of constant interest and amusement to me.

Being a mother often requires a sort of generalist or Jill-of-all-trades expertise -- part nurse, playmate, chef, maid, bodyguard -- with endless distractions. It is so different from writing, where single-minded concentration and discipline is usually needed. How do you reconcile the two?

I write while my daughter is at school, and don't even try when she's around -- she's too old for naps now.

Do you have any advice for struggling single mothers?

I am never very comfortable giving other single mothers "words of advice." Nobody knows better than I do that I was very lucky -- I didn't need money to exercise the talent I had -- all I needed was a Biro and some paper. Nor do other single mothers need to be reminded that they are already doing the most demanding job in the world, which isn't sufficiently recognized for my liking.

I have read that Warner Brothers bought the film rights to "Harry Potter." How do you feel about Hollywood re-creating your characters?

A mixture of excitement and nervousness! I do think "Harry" would make a great film, but obviously I feel protective towards the characters I've lived with for so long.

How do you envision your future?

Well, I'll be writing, and that's about all I know. I've been doing it all my life and it is necessary to me -- I don't feel quite normal if I haven't written for a while.

I doubt I will ever again write anything as popular as the "Harry" books, but I can live with that thought quite easily. By the time I about Harry, I will have lived with him for 13 years, and I know it's going to feel like a bereavement. So I'll probably take some time off to grieve, and then on with the next book!