Philip-Lorca diCorcia. (Portfolio).

This time Philip-Lorca diCorcia's stage set is Mayor Giuliani's tarted-up Times Square, although you'd hardly guess it from the pictures. The photographer's signature electronic flash units are hidden in a walkway beneath a contractor's scaffolding, which serves the added purpose of shielding the passersby from any other light. An X taped on the sidewalk marks the spot at which the striding figure will catch the flash and come momentarily into focus for the camera, which is planted far enough away to escape notice.

Or perhaps you might guess the place. Picked out against the dark void, cropped to head and shoulders, strangely static although all are in motion, diCorcia's figures are reduced to types or--thanks to the pristine four-by-five-foot prints--elevated to archetypes: the Mailman, the Young Blonde, the Rabbi, the Black Executive, the White Teenager, and so on. The four pictures reproduced here are extracted from "Heads," an ongoing series begun last year and conceived as a whole--a contemporary catalogue of public identities. It's a community of people who have never met each other, nor wish to: today's Times Square at ground level, below the blaring spectacle.

What's behind the mask? The pictures decline to answer the question--but do they even raise it? One might say instead that they invite us to consider why we are more likely to ask that question--or to expect an answer--while looking at photographs in a gallery than while standing on the street.

DiCorcia made his first mature pictures more than twenty years ago. His work- both his independent art, inflected by the high craft and glitter of commerce, and his commercial work, inflected by the critical wit of an artist--has steadily evolved ever since. What began as a refreshing slap in the face of photographic realism (thanks, we needed that) has never lost its theatrical polish. But, as diCorcia's subjects gradually mutated from the intimate to the anonymous, from family and friends to Hollywood hustlers to passersby who rarely even notice that they have been photographed, his fictions improbably absorbed the weight and ambition of what some people still insist on describing as photography's more innocent documentary past.

Improbably, but not unintentionally. Looking at these new pictures, you might notice that Walker Evans and Harry Callahan have been here before. DiCorcia, who has a firm grasp of photographic history, noticed it too. He went ahead anyway, possibly because he was approaching the territory from a different direction and so figured that it might look different to him--and it does. As always, the mise-en-scene is rigidly defined. Except for choosing among the characters who unknowingly audition for his cast, however, the photographer is powerless to direct his actors. Even the instant of exposure, precisely dictated by the X on the sidewalk, is out of his control. DiCorcia's old blend of fiction and fact has precipitated into extremes: absolute control and passive observation, cinematic drama and slice-of-life realism, melded by a stubborn confidence that tradition can serve as a springboard to invention.

PETER GALASSI is chief curator of photography at the Museum of Modern Art, New York. He recently organized "Andreas Gursky," the first US retrospective of the German photographer's work, and "Walker Evans & Company," a wide-ranging exploration of Evans's impact on twentieth-century art, which travels to the J. Paul Getty Museum this summer. In 1998, Galassi was cocurator of "Aleksandr Rodchenko," and in 1997 presented the complete set of Cindy Sherman's "Untitled Film Stills," 1977-80, which MOMA had acquired in 1995. In this issue, he introduces a portfolio of new photographs by Philip-Lorca diCorcia, whose work Galassi featured in an exhibition of 1993 and a book of 1995. PHOTO: TIMOTHY GREENFlELO-SANDERS