It's no secret any more. Record anthologies have been compiled, lengthy articles published and a special jazz festival is even held each year -- all aimed at the once-overlooked role women have had in the development of jazz. Heading the list of contributors is Mary Lou Williams, who is appearing this week at Blues Alley.

With a career that spans five decades, Williams is uniquely equipped to instruct the listener on the evolution of jazz. She opened last night with a solo journey from spirtuals to bop, her left hand becoming stronger and more insistent with every step.

Her ragtime may be too fast for some and her boogie may lack the florid passages of an Albert Ammons, but few pianists can rival Williams' varied repertoire or her two-fisted style. After drifting into an easy stride with bassist Milton Suggs providing support, Williams launched a sprightly swing arrangement of "They Can't Take That Away From Me," later making room for her distinctive brand of bop 'n' blues.

With Billy Taylor's "A Grand Night for Swinging," she had the audience popping their fingers like so many flashbulbs at a rock concert.

Yet another side of Mary Lou Williams will be on display Sept. 5 at Ford's Theater. She'll perform "Mary Lou's Mass" with the Howard University Choir.