What kind of French singer is this? You couldn't help wondering, last night at the Kennedy Center, when the band struck up "Waiting for the Robert E. Lee," and Mireille Mathieu made her first entrance singing, "J'ai envie de chanter."

The answer emerged in the next two hours: Mathieu is a highly polished, versatile, eclectic singer, a disciple of Maurice Chevalier and a total pro. She works best in her own language, of course, but seems almost as fluent in Spanish ("Solamente una vez") or German ("Die Tage der Liebe, wie Rosen so schoen"). Her English is clear, though lightly accented (making "feel" sound a bit like "fill"), and when she sings "People," the Streisand imitation is more than passable.

For her Washington debut last night, the Concert Hall was packed tight with knowledgeable fans, who would begin to applaud in the opening bars of a favorite number such as "Une histoire d'amour" or "Oui, je crois." Mathieu fulfilled their expectations; she falls slightly short of artists like Be'caud, Piaf or Aznavour--the kind of singer who always leaves a bit of blood on the stage--but she is a superb entertainer with a fine voice, a good sense of melodic line, phrasing, pace and variety. She was supported by a large ensemble, including six expert dancers who must have changed their costumes a dozen times (almost as often as she did), three backup singers and a band that stopped being too loud whenever she stepped on stage.