Kevin Eastridge, 7, sporting a black, pointy hat, Harry Potter-style glasses and a lightning-bolt tattoo on his forehead, was the first at the Barnes & Noble in Bethesda to get a copy of the latest installment in the J.K. Rowling series early this morning.

Like Harry Potter fans across the country, Kevin, of Georgetown, got to the store early yesterday. He was the first to get a wristband -- and was therefore first to get a book.

As the sales clerk handed him his bag, he stuck his tongue through the gap in his front teeth and gave a grin, his eyes widening. "It's good to have it now," he said. He planned to rush home with his mother to read the first chapter before he went to bed.

Even before Washington area booksellers unsealed the latest Harry Potter tome just after midnight, the book was on its way to shattering single-day U.S. sales records.

Six years ago, when the Harry Potter franchise had secured global word-of-mouth, Scholastic Inc. introduced the third installment with a first printing of 500,000 copies. Yesterday, Scholastic -- Rowling's U.S. publisher -- said it expected to surpass records set by all previous Potter books by selling more than 5 million of the 10.8 million printed copies in the first 24 hours.

As recently as 2000, the initial print run for "Harry Potter and the Goblet of Fire" was a mere 3.8 million.

"There's no greater sense of wonder in the book business, and I've been doing this for 30 years," said Steve Riggio, chief executive of the 800-store Barnes & Noble chain.

The wonder is partly stoked by sophisticated marketing and the growth of online bookselling. Scholastic's strategy started with intense security measures, hoping to make sure no copy of the book got out before midnight. Then there were the preorder sales: more than 1 million through Barnes & Noble, more than 1.4 million through and hundreds of thousands more at stores across the country.

And then there are the Potter parties, which grow with each installment. At the Bethesda Barnes & Noble, throngs of children and their parents lined up in advance of a late-night fete that featured a wizardry school, make-your-own magic wand and picture frame stations, costume contests, tattoos and more. Stores across the Washington region planned similar events.

As midnight approached, 40 or 50 employees worked to keep the long line of Potter fans in order. The growing excitement was heightened by a New Year's Eve-style countdown.

Katie Stanger, 10, of Bethesda, came in her purple magician's cape and pointy black and silver-starred hat. She and her 8-year-old sister, Maggie, said they could not wait to read the next Potter installment; the series' mystery hooks them in.

"We're going to stay here until we get too tired to stay anymore," said Maggie, who came as her favorite character, Hermione the witch, in a black dress with red trim.

A loud cheer went up at the Borders on Lee Highway in Fairfax County as the first numbers were called out at 12:03 a.m. Peter Taves, 16, of Fairfax Station was the first to receive a copy. He had arrived at the store about 5:30 a.m. to get his numbered wristband.

At the District's Politics and Prose on Connecticut Avenue NW, a fire-eater entertained a large crowd at the bookstore's parking-lot party as they waited for midnight.

Leonard M. Lodish, a professor at the University of Pennsylvania's Wharton School, said it all begins with an infectious love of the characters, spread from child to child.

"Kids talk to each other, and word of mouth is the most powerful marketing medium there is. This is a good example of it," Lodish said. He added that the midnight sales rush has increased the hype, a method tested a decade ago when Microsoft released Windows 95. "To have it all come to one point in time is a very good strategy," Lodish said. "You can't knock it."

About 10 million copies of "Harry Potter and the Half-Blood Prince" are expected to be sold worldwide today -- 2 million of them in Britain, Rowling's homeland.

The marketing juggernaut has not been without flaws. Several copies of the book were mistakenly sold early. A 9-year-old New York boy got a copy of the book, but he returned it after reading only a few pages. As a reward, Scholastic reportedly sent him a goodie bag. Copies of the book were sold early in Indiana and Canada.

David Snyder, who organized the Potter sales effort at the Borders store in Largo, including last night's party, said: "It's kind of like Christmas morning. That's kind of the suspense."

Borders stores are selling Magic Berry Smoothies and Lightning Bolt Treats for $1.99, as well as Bertie Botts Every Flavor Beans (jelly beans), Chocolate Frog candies and Drooble's Best Blowing Gum.

In New York, Barnes & Noble transformed its flagship store at Union Square into an amusement park of sorts, building a Diagon Alley with a live-animal magic show, an Olivander's wand-making station and an apothecary potion-making stand.

Online retailers sold the book at a steep discount, promising to deliver it to readers' doorsteps today. and Barnes & Noble are selling copies for $17.99, a 40 percent discount from the cover price.

Markdowns did not seem to be on fans' minds early this morning, though. At the Borders on Lee Highway, 15 staff members at eight cash registers worked steadily, ringing up sales.

Kelly McCullough, 17, of Chantilly had ticket No. 14. She came with her best friend, and her sister was waiting in a car outside. The plan had been for her to start reading the book to her sister during the 10-minute drive home. But, she said, she knew she would not be able to put it down.

"I can't start it and not finish it," Kelly said.

Staff writer Jacqueline L. Salmon and the Associated Press contributed to this report.

John Hobson, 11, and John Park, 12, dress up at Fairfax Borders.