It'sbeen a big year for Anita Baker -- since she was last in Washington, she's seen her second album, "Rapture," go triple platinum, and she's harvested a truckload of Grammys and such.

But Baker hasn't been content just to bask in the reflected glow of award plaques and shiny discs. In her Saturday concert at Constitution Hall, the first of a four-night stand, Baker showed she has developed into a sophisticated concert performer. She is still (adorably) giddy at times, but she has also become more at ease on stage -- easily directing her band, inventively varying her phrasing on by-now familiar songs, and chatting affectionately with the audience. She even spontaneously altered the program to accommodate a fellow who kept pleading loudly for "Been So Long."

She sang all the songs on the "Rapture" album and more, exulting in long dramatic glides and swoops on smooth soul ballads like "You Bring Me Joy" and "Angel," and handling upbeat numbers like "Watch Your Step" with sassy authority. She's firmly rooted in R&B and soul styles, but fronting a nine-piece outfit with four backup singers she comes as close to a contemporary big band singer as anyone we have. This was best seen in her jazzy handling of two new George Duke arrangements, a brassy version of Van Morrison's "Moondance" and a bluesy "God Bless the Child."

The evening suffered from some show biz pitfalls. The sound balance was disturbingly uneven, and each member of her Hubba Bubba Band was given valuable concert time for uninspired riffing and soloing. But Baker herself fairly glowed, and her elegant brand of ultimate make-out music warmed up a very cold night.