The Alvin Ailey American Dance Theatre offered an all-Ailey program for its second evening at the Kennedy Center last night, showing two instances of the choreographer at his inspired best, and in a third case, what might be called an inspired failure.

The program began with its weak link, "The Mooche," originally created in 1974 for an Ailey-Ellington TV special and revised the following year for the stage. It's inspired on several counts, first of all the electric but understated glamor of Rouben Ter-Arutunian's set, its art-deco neon and mirrored panels evoking so vividly the ambiance of a fashionable cabaret. Randy Barcelo's sleek, florid costumes make a perfect complement.

There's also Ailey's central idea, which was to match Ellington's musical portraits of notable black women entertainers -- singers Florence Mills, Mahalia Jackson and Bessie Smith, and dancer Marie Bryant -- with dance equivalents. The choreography, however, never quite lives up to the conception, relying so heavily on formula and artifice that portraiture turns almost into caricature, despite the mostly skilled efforts of the Ailey soloists, including Judith Jamison as Bessie Smith. (The exception is Ronnie Favors, who does not cope well with her tap solo, as staged by Charles "Cookie" Cook.) Nor does the final image (borrowed from Jooss' "The Green Table") of Smith's death, presided over by Ku Klux Klanners, achieve the poignancy it strives for.

The very shortcoming of "The Mooche" becomes the triumph of "Masekela Language," as Ailey's depictions of character types in a South African saloon demonstrate the power of his theatrical perceptions when they are dead on target.

Last night's performance also caught the piercing quality of the choreography, from the defiant truculence of the opening poses to the individual characterizations -- Sarita Allen as an impetuous loner; Alistair Butler as an angry, mesmeric leader; Judith Jamison as a woman of refinement and inner torment; Marilyn Banks as a sexy vamp; and Ulysses Dove as a torn and desperate fugitive. Other factors conspire in the perfection of form, including such pithy props as an idling fan and a recalcitrant jukebox, which so deftly suggest the sultry, claustrophobic atmosphere; Chenault Spence's melodramatic lighting, which for once is in ideal accord with its function; and, hardly least, the soul-searing eloquence of Hugh Masekela's music, the message of which Ailey has so aptly divined.

The evening concluded forcefully with a repeat performance of "Memoria," Ailey's impressive new tribute to the late Joyce Trisler.