Fifteen years after J.K. Rowling’s Harry Potter and the Sorcerer’s Stone first graced U.S. bookshelves, Scholastic is touting some impressive numbers. The in-print tally for that book and the subsequent six Harry Potter novels has topped 150 million copies in the U.S. alone. Published in 200 territories in 74 languages, the series boasts worldwide sales of more than 450 million copies. To mark Harry Potter’s 15th U.S. anniversary, Scholastic is staging a contest in which 15 public libraries will win a party pack to help them host a celebration in honor of the bespectacled young wizard.

The winners will be announced on July 31 – Harry’s birthday – and the parties will be held on August 27, the U.S. pub date of new trade paperback editions of all seven books in the series, which feature new cover art by Kazu Kibuishi. Scholastic will simultaneously release a boxed set of the new paperbacks, which like previous editions will be published under the Arthur A. Levine imprint.

The contest entry form, available online, asks contestants to describe the party they’d plan at their libraries to celebrate the anniversary and welcome new readers to the world of Hogwarts. The 15 winners will receive 100 copies of the new trade paperback edition of Sorcerer’s Stone to give away at their celebrations; a copy of the new boxed set, signed by Kibuishi; a $100 gift card to help host the party; and an event kit that includes sticker sheets, name tags, bookmarks, and activities. (Event kits are available to all librarians and retailers.) The entry deadline is July 17.

“Librarians have always been an integral part of sharing love of Harry Potter,” said Stacy Lellos, Scholastic’s v-p of trade marketing and multi-platform publishing. “When we were talking about planning our outreach for the new trade paperback editions, we knew that librarians needed to be a critical piece of that and that we wanted to reach out to them specifically. Like stores, libraries had great celebrations for each new book in the series, and this will give them the opportunity to host another party to help share Harry Potter with their patrons.”

Due out with first printings of 100,000 copies each, the new trade paperbacks will have a slightly more vertical trim size than the current digest paperback editions, which feature cover art by Mary GrandPré. Those digest paperbacks, as well as the hardcovers, will continue to feature GrandPré’s art. “The original Harry Potter cover art is beloved by us all here,” said Lellos, “but we wanted Kazu Kibuishi, who’s also a talented artist, to bring his vision to the trade paperbacks, not only to speak to existing fans, but to introduce a whole new generation to Harry Potter.” The new editions include chapter samplers for the next book in the series.

The covers of the new trade paperbacks of books three through seven will be revealed via various venues between now and July 31 (the cover of the first was revealed on Good Morning America and the second at BEA). Scholastic has created a animated Harry Potter trailer to promote the new editions, which will run in theaters as a preview to Percy Jackson: Sea of Monsters and on cable TV in select cities.

The new editions will also be featured on the updated Harry Potter Reading Club Web site, where the winners of the 15th anniversary contest for librarians will be announced. Various Scholastic staffers, described by Lellos as “our longtime Harry Potter team,” will judge the contest. She looks forward to seeing librarians’ responses to the contest’s challenge. “Librarians have been so important to the success of the Harry Potter books,” she says, “and we’re very eager to hear what ideas they come up with to celebrate this anniversary.”