In the unpredictable flux that for the most part characterizes the Washington area's modern dance scene, there appears to be one steady constant -- the admirable Maryland Dance Theater, now more than a decade old and going very strong. Last night's splendid program at the Publick Playhouse once again demonstrated the group's unfaltering brilliance.

From its nature as a touring repertory troupe, and with the help of a home base at the University of Maryland, multiple funding sources, and clearsighted leadership from artistic director Larry Warren, MDT has been able to achieve an order of stability, a level of professionalism and an artistic maturity that elude many other organizations.

Paradoxically perhaps, change is as much an inherent MDT trait as constancy. Part of the ensemble is drawn from the ranks of U-Md. students, who inevitably pass on to other pursuits or precincts; about two-thirds of the present season's dancers are new to the troupe this year. The repertory, too, is ever shifting, as the company seeks to expand its horizons and keep itself fresh. On last night's program, four of the five offerings were premieres of one sort or another.

The most striking impression was left by Warren's own new "Groundplan," a phantasmagoria in nine sections set to atmospheric music by George Crumb. Like Warren's previous pieces for MDT, it is technically deft, imaginative and diverting. It's also a bit diffuse, but some post-hoc trimming and tightening may well alleviate that. The dramatic premise is a tour of the creative process itself -- Alvin Mayes portrays a choreographer caught in the act, so to speak; we watch him meditating, sketching ideas, trying them out, and interacting with his own visions, which include slinky sirens, a gothic funeral procession, a bunch of zanies and other things. In the final section, everything he's conjured up passes in review before his, and our, eyes, before he's left alone on stage with his "laboratory" dancer (Anne Warren), vibrating with creative frenzy. It's all done with the mixture of fantasy, levity and verve that is Warren's choreographic signature, and it's a tour de force of another sort; the work manages to make effective use of the entire company, all 17 dancers.

A new restoration (by Anne Warren from the Labanotation score) of Doris Humphrey's 1931 classic, "The Shakers," had the requisite energy and precision, but, as yet, not quite the sledgehammer force and poignancy latent in the work. The insufficiency had nothing to do with technique or even stylistic authenticity, but with internal conviction, the key to the work's impact. The performance of the Humphrey-Currier "Brandenburg Concerto," by contrast, achieved full depth for the first time since its acquisition last year -- these things take seasoning. Anne Warren's newly revised "Damascene," to delicately exotic music by Lou Harrison, is an appealing study in sensual, curvaceous lyricism.

The major disappointment, despite its physical exhilaration, was "And . . .," by New York choreographer Matthew Diamond. Like the synthetic, spacey Jean Michel Jarre music to which it is set, the choreography is facile and forgettable, all manner and effect. It got a sparkling performance, however; in general, this year's crop of dancers seems exceptionally handsome, vivacious and well-matched, with no less than eight stalwart males (ever a rare breed).

The one somewhat dismaying note to this fine evening was the relatively narrow stylistic compass of the programming; at this stage in its evolution, MDT could afford to be a little more daring, on new frontiers and old. As things stand, the repertory is both too one-sided and too "safe." How about, for example, some Lester Horton, or Charles Weidman, or Yvonne Rainer or Meredith Monk?