Thanks to the relentless alacrity of modern science, we can now identify and treat many of the gravest behavioral dysfunctions of the middle class--from the gruesome financial hemorrhage of Running-Shoe Fetish to the humiliation of Fondalepsy (violent aerobic seizures triggered by recorded music, also called Simmons' Palsy or St. Jane's Dance) to the near-epidemic occlusion of the auditory canal known as Walkman's Oblivion.

Yet medical research has virtually ignored one of the most exquisitely painful of these disorders: Premature Ski Syndrome, the maniacal compulsion to hit the slopes in the off-season.

The early warning signs are all too familiar. You go down to the kitchen in the middle of the night and discover your spouse, outlined in the eerie glare of the refrigerator light, standing motionless and gazing forlornly into the freezer. To the neighbors' astonishment, you begin using ski poles to plant the nasturtiums. You find yourself uncontrollably doing deep knee bends down the Metro escalator.

For decades, the only known cure was a painful surgical cashectomy, in which the checkbook was cut open and enough money removed for a summer trip to Chile. But in recent years, technology has evolved a less drastic palliative: grass skiing. All you need is a slightly atrophied instinct for self-preservation and the willingness to be shod with two-foot-long aluminum roller gizmos that look like mutant Tonka-toy tank treads and are only marginally less treacherous than the dreaded M Street rental roller skates.

For those desperate to ride the wild turf, the nearest venue is Ski Liberty, 60 miles away amid the cloud-dappled hillscape of southern Pennsylvania. Among the advantages: a short drive, a long season (weekends and holidays from May 28 through October), the Alpine Slide for the nippers (fiberglass sleds in a concrete trough) and a fee of $10 for three hours whether your bring your own boots and poles or use Liberty's winter rental gear. (By all means, use theirs: The walk to the chairlift crosses a field generously littered with gravel, mud and rocks.) Still better: On a recent magnificent Saturday, the sparse crowd included only two skiiers.

It's even safe for acrophobes. Liberty, with its 600- foot vertical, is no Mont Blanc; and grass skiing is limited to two short trails on the lower half of the easy side. Nonetheless, the management burdens the prospective meadow-jockey with a fistful of liability waivers for his signature before sending him to the fitting room and the "skis"--available in lengths from 1 to 3 feet (the longer the faster) and powerfully ungainly at any size.

Each consists of a metal framework holding a number of rollers around which revolves a 2-inch-wide nylon belt, cleated at intervals for traction. The whole rig looks like something that fell off a hay baler. Worse yet, you discover that the last release you're going to see is the one you signed in the office: The boots clamp firmly and immovably to the skis' top plate, leaving you a disconcerting 3 inches off the ground with no way out but down. The attendant's offer of knee and elbow pads may not be fully consoling.

Thence to the chairlift. Some might call it slow, but it is pleasant to look down and watch the snails racing by and observe the seasons changing. It finally scoots you out, revealing that the slope, which looked so soft and green from below, is actually a scabbed and lumpy amalgam of grass, dirt clods, weeds and rocks. (Inexcusable, considering that Liberty has had the sport for four years--during which time even the most inept sluggard could have turned those few hundred yards into a putting green.) Caution: Getting used to the skis in the baking sun can produce a certain deficit of elegance. To practice in advance, you might go to the steam room and try doing the foxtrot in a tub of Quaker State. Then push off with the poles, think of Aspen, and you're skiing--up to a point.

The point comes about 10 feet down the run, when you realize that most of what you know about skiing is not quite applicable: The skis will barely flex and therefore will not carve; weighting the tips will only pitch you forward when they drop into a rut; you can't cheat by skidding a turn, since the equipment will only roll, not slide; the surface you are repeatedly flung upon while making these discoveries is markedly less congenial than snow. And if you had visions of a neat christie stop that throws up a smart spray of grass clippings, forget it. You can stop only by turning all the way uphill and hoping that gravity will do the rest. (Note: It is best to discourage spectators during this learning phase. Some idlers later remarked that, from the bottom of the hill, our tester "looked like a wino in a sack race.")

But in an hour or so, you find you can turn the things predictably, if not quite gracefully, by merely exaggerating some normal motions of snow skiing--dropping the knees hard to the inside of the turn and thus canting the nylon belts up on edge. Soon you're doing broad giant- slalom arcs, even tight linked turns, all the while grinning like an imbecile, sweating like a plow horse and rattling your molars loose on the stubble-pocked surface. And after three hours, even the most grievously afflicted PSS sufferer will be cured: Freed of his nagging compulsion, bereft of several pints of body fluid and likely prepared to wait almost indefinitely for the real thing.