The bookstore at the National Museum of American History, long run by McGraw-Hill, will be taken over by the Smithsonian Institution as of July 1, Joe Chmelik, director of the Smithsonian's museum shops and acting business manager of the McGraw-Hill bookstore, said yesterday. The New York-based publishing empire has run the store for 10 years as a general bookstore with a special concentration on the arts and sciences.

"There is no unhappiness with McGraw-Hill. Their contract expired. It's as simple as that," said Chmelik. "The Smithsonian felt we would like to run this one as we do our own museum shops. We've got nine of them, you know, and each one has its own bookstore."

"Ten years ago when the Smithsonian asked McGraw-Hill to operate the store, to act as a concessionaire in fact, it was because we were absolutely swamped with running the eight other stores. Now we feel we can run it just as well as McGraw-Hill, and ultimately, we'll save money for the taxpayers. This way we take out the middleman," Chmelik said. "It's important also that everything we sell be related to the collections. This will be more of a resource of sorts. It will be more specialized."

John Letterman, McGraw-Hill's buyer for the bookstore, said changes have already been made. "What we've cut out for them are all professional, academic, technical, social science, religious, philosophy and anything else that is outside the border of the United States . . . They are making an effort to have a nice selection of Americana and items exclusively related to the museum. I should think they will do a better job with folk art, for instance, simply because they have a narrower focus now."

"We're in the business of retailing more than McGraw-Hill is, believe it or not," Chmelik said. "We have nine bookstores, they have three. They're not in the bookstore business. They're a publishing house."