One of the year's most satisfying developments has been the dramatic evolution of Rickie Lee Jones' talent. Just last April at the Wax Museum, she gave a concert that far transcended her recorded work in its scope and impact. Last night at the Merriweather Post Pavilion, she proved that she has improved since then in every way -- as a singer, as a bandleader and as a stage personality.

Playing for one of the biggest audiences of her life, she filled the open hall easily with her big, ringing voice and impromptu style.

Her band has expanded from eight to 12 members; it now features a crack four-man horn section and two singers who can match her inspired bop improvising. Her 22-year-old piano prodigy, Michael Ruff, stood out in the superb band with his jazz solos and scat vocals.

The Mardi Gras-flavored horns punched up her hit single "Chuck E.'s in Love" and the New Orleans classic "Iko Iko." Jones' own bop rap numbers straddled the boundary between singing and acting. On the Coasters' "Shopping for Clothes," a roadie played a sleazy tailor who brought out a rack of clothes and engaged Jones in wicked repartee.

Far more serious was Jones' version of "We Belong Together." She sang the defiant lines with resonance and unassailable certainty. She pulled off an aching version of Lowell George's "Long Distance Love," sitting alone on stage at the piano. Her range has expanded steadily, especially at the top end. Thus, she was able to jump up for high octave harmonies. On "Living It Up," she sliced through her own high, sailing voice to cry out "Oh, tell me where you are" in sharp desperation.