Where do you go to buy a first-rate contemporary American print?

For years, people have been asking that question, and for years the Jane Haslem Gallery has been one of the best answers, not only in Washington but throughout the country. Her summer show reveals why.

Selected from offerings illustrated in her posh new catalogue, this show unveils the formidable sweep of American 20th-century prints, drawings and paintings available in Haslem's stock.

There's a sense of rediscovery here, of high and persistent talent occasionally eclipsed by the shifting limelight of fame. Mark Tobey is a major example, an artist of supreme grace, beautifully represented here by a feathery blue and white aquatint, yet rarely seen these days. Since the mid-century renaissance in American printmaking. Haslem has specialzied in work by the leading graphic innovators -- Mauricio Lasansky, Gabor Peterdi, Misch Kohn, Antonio Frasconi, Leonard Baskin -- and their mastery seems more impressive now than ever before.

Lasansky's latest giant-sized print, "Emilia at 10 With Black Cat," is sheer spectacle, while Gabor Peterdi's fabulous drypoint etching, "Surging Wave," is beginning to look like one of his masterpieces. Peterdi himself, in fact, is beginning to look like an artist of far greater talent than he has ever been given credit for. One defeated presidential candidate received Haslem's catalogue and rushed in to buy two Peterdi paintings. He's obviously got a better eye for art than he had for national politics.

There are many others: Will Barnet, Anthony Gorny, Leonard Lasansky, Richard Ziemann and Moishe Smith. There are good contemporary realist painters, including Billy Morrow Jackson and John Winslow. There are talented newcomers like Jeri Metz, who has made a poignant pencil drawing of a "bag lady."

At the front of the gallery is a new group of artists -- at least new to Haslem: wood engravers, most of whom worked as illustrators in the '40s and '50s, and whose prints had not been taken seriously until the recent revival of interest in early 20th-century American art. Lynd Ward, now retired and working in Reston, offers one of the best boys in town at the moment: a 1953 wood engraving titled "Corral," and reminiscent of Thomas Hart Benton. The price: $50. Bernard Brussel-Smith's slightly cubistic city scenes from 1949 are also more striking, as are the better known works of Clare Leighton. Prints by Edward Hopper, John Sloan and Martin Lewis are tucked in here and there.

Haslem has always dealt exclusively with handmade prints, so there is never any question of "originality" here. The atmosphere is welcoming, and the works always available for viewing. The gallery is located at 2121 P St. NW, and has special summer hours: 12:30 to 5:30, Tuesdays through Fridays. Buried Treasures

Mickelson Gallery, 709 G St. NW, is winding up a summer group show of prints today, a reminder of the treasure still buried in its permanent stock.

Years ago, proprietor Sidney Mickelson thought that lithographs by American artist George Bellows were selling too cheaply, so he bought dozens of them. He also loaded up on the probing etchings of Jack Levine, and the visual puzzles of eye-boggler M.C. Escher, for whom he was the first exclusive dealer in America.

An assortment of prints by each of these artists is included here, and though the choice is no longer complete, there are good works to be found by serious print lovers willing to burrow, particularly among the works by Bellows. "The Wedding," "Anne" and the powerful "Benediction in Georgia" are all still here, along with one of the two popular lithographs entitled "Tennis (Tennis Tournament)." There are also prints by other well-known Americans, including Fairfield Porter, Richard Anuszkiewicz, Ben Shahn and Leonard Baskin.

Mickelson also has involved himself with several contemporary printmakers, and they, too, can be seen in this show and thereafter. One of the most charming newcomers is Korean-born Kay Yun Gim, who makes color etchings that juxtapose the Orient with the Western world in images that suggest the dichotomy she faces as an Oriental artist working in America. "Melancholia in Exile" is one of the most revealing titles; "A Girl with Guernica," the most charming image. It shows a young woman in traditional Oriental dress standing before Piscasso's masterpiece.

Victor Huggins' "Appalachian Landscape," Florence Putterman's "Salem Valley" and Minnie Klavens' abstract silkscreens are other works worth looking at on the walls, through today, and thereafter by request. Sculptures & Mannequins

Washington artist Mildred Thompson, just back from successful shows in Germany and France, is making a highly visible return -- of all places -- in the 7th and F Street NW windows of the Hecht Company. Twenty abstract wood sculptures, including several new small-scale works, stand forthrightly and unoffended next to mannequins who gain a good deal in the bargain. To help get her art to the people, Thompson has kept the price ranged down (from $350 to $2,000) and Hecht's has agreed, by special arrangement, to permit buyers to charge the works on their major credit cards. The show will be on view through Aug. 4.