"The Decline . . . of Western Civilization" is a bracing primer to just about anything one might want to know about the hard-core punk scene. At the same time, it's remarkably evenhanded, making no judgment on the musical or social standards of the movement. Director Penelope Spheeris neither champions, patronizes nor condescends to the participants' stylized fury. The result is a film that will appeal equally to the furious and the curious, assuming that both enter the arena with an open mind.

The well-shot and tightly edited color film is a volatile mix of performance shots, band-at-home interviews and confrontations with denizens of the punk underground. The featured bands are headed by the much heralded X and Fear (of recent "Saturday Night Live" notoriety), and include Black Flag, Circle Jerks, Alice Bag Band and Catholic Discipline, whose lead singer explains, "There's no more brotherhood. We're not grooving on the same vibe anymore. Everybody's grooving on his own vibe . . . an ugly vibe."

The music, rejecting the complexity of the '70s, is brutally fast, 90-second sonic assaults to which Spheeris has (wisely and frequently) added subtitles. And though the music and the slam dancing are fascinating, it's the interviews that are revealing. The band members, for the most part, come off as alienated but essentially bright kids; it's the shaved-head fans, shot in black and white against a concrete wall lit by a bare light bulb, who put the scene in a social context. Eugene, a 14-year-old, struggles to explain his isolated nihilism and anger: "Well, with me, it comes from being in this city, seeing all the ugly old people, the buses . . ." He admits that mostly he stays alone.

That's the down side, but there's a spunkiness about the singer for Black Flag who seems content to live in a closet because it only costs him $16 a month; there's a genuine playfulness and camaraderie among the members of X. There's also a lot of posturing and petulance, but one walks away from "The Decline" less scared than informed. Unlike most rock films, it gathers information about this curious convergence of art, politics, fashion and morality (the punks are curiously sexless and anti-drugs) and shuffles it into a cohesive overview.

Spheeris seems unworried about the jagged music and appearance of the L.A. punks. One senses from her film that the frenetic energy that seems irrationally violent is actually narrowly channeled. The punks may be as guarded and inaccessible as the idle rich, but they seem intent on being dangerous within limits and only to themselves. Addressing the result of teen-age frustration, despair and cynicism rather than its causes, "The Decline" suggests the meaning of subculture in a manner that's seldom encountered on celluloid. You don't need to be a Weatherman to tell which way that wind is blowing.

"The Decline" shares the screen at the Dupont through Thursday with "D.O.A.," a film about the 1978 tour of America by the notorious Sex Pistols.