It was a genuine treat to see the Pennsylvania Ballet making its debut appearance at the Kennedy Center Opera House last night, long after other major cities have had the pleasure. The Center's ballet offerings of the past have been lavish on the international side, but much too skimpy when it comes to the domestic scene for a place that calls itself a national cultural center. And as the Pennsylvanians made clear last night, this is one of the country's outstanding classical ensembles.

It's unfortunate, however -- from several standpoints -- that the troupe should have had to make its first Washington appearance as a "replacement" for American Ballet Theatre, which has been immobilized by a contractual dispute. The perspective is skewed, leading to fruitless and misdirected comparisons.

We Washingtonians have prided ourselves in recent years -- and justifiably -- over the sophistication we've acquired in the ballet realm. Certainly we're perceptive enough to know the difference between an ABT and the Pennsylvania Ballet, though this takes no great measure of connoisseurship. On the basis of the relatively tepid reception the latter received from its first night audience, however, one wonders whether we're sophisticated enough to appreciate the Pennsylvania company for its own very real virtues, divorced from superstardom, celebrity chic, deluxe furnishings and other artistic irrelevancies. It's well to keep in mind, too that in order to accommodate that Kennedy Center's need, the Pennsylvanians had to whip this week's programs together in mercilessly short order, and the results aren't likely to be the same as what they might be given adequate time for preparation and planning.

Such provisos aside, last night's inaugural program seemed splendid. What we saw was a beautifully disciplined and aware ensemble with an abundance of both verve and finesse.

We are indebted to the Pennsylvanians also for bringing us the Washington premiere of still another ballet by the prolific Choo San Goh of the Washington Ballet, who has been rising so rapidly in national esteem we can hardly keep up with him. "Carsella 1, 3, 4" set to the respectively numbered movements of Alfredo Casella's "Paganiniana," is far from Goh's strongest composition -- the ending is pallid, and even some of the work's most striking ideas don't seem to have found a comfortable relation to the whole.

Still, not just in its best realized passages -- the beautifully expressive body sculpture of the slow movement, for instance -- but from start to finish this is the work of a choreographer whose native language is dance movement. If the piece shares the unevenness of its score, it is also sensitive to the rhythms and textures of the music in ways only a major talent can muster. The performance came under the heading of a valiant but insufficient try, and showed that it's not only Washington dancers who are challenged beyond their means by Goh's complex demands.

The company was at its most winning and impressive in a brilliantly mounted rendering of Balanchine's "Raymonda" Variations. Ballerina Magali Messac, handsomely proportioned, suave and incisive in phrasing, would be stunning in any troupe, and she was adeptly and stylishly partnered by William DeGregory. Dana Arey's musicality and the exquisite precision of Victoria Lyras were further enhancements.

Lichine's frothy "Graduation Ball," which one would think ideal for this exceptionally youthful appearing troupe, was disappointing, mainly because the frenetically farcial treatment slighted the sentimental elements which can make the ballet not just amusing but endearing.