When Michele Norris joined National Public Radio in 2002 to host its popular afternoon news show All Things Considered, she made history as the first black woman to host a major weekday show at the public radio outlet.

But you won't find that achievement in the new book about the news organization's 40-year history, This Is NPR, because Norris was left out of the book completely.

"I'm disappointed," said Norris, who declined to speak in detail on the issue when contacted by telephone. "But you have to ask NPR why it happened."

Norris was asked to contribute a chapter, along with other staffers or people who appear regularly on NPR for the book, which weaves the stories into a chronological history. Other contributors include Cokie Roberts, Nina Totenberg, P. J. O'Rourke and Paula Poundstone. But because she was writing her own book, The Grace of Silence: A Memoir, Norris couldn't contribute an essay and was not included anywhere else, said NPR spokeswoman Dana Davis Rehm.

"It was an inexcusable mistake," Rehm added. "She should have been in the book."

The error comes as NPR weathers criticism over diversity issues for its decision last month to let go news analyst Juan Williams, then one of only two black male on air staffers at NPR.

After Williams' ouster, the National Association of Black Journalists released a statement titled "diversity is better but not enough," challenging the news organization to better reflect the nation's diversity in its staffers appearing on air and in management.

The book's index also doesn't include Williams or the African American Public Radio Consortium, a coalition of black-focused public radio stations which helped NPR develop shows featuring Tavis Smiley, BET host Ed Gordon and Farai Chideya, all of whom have since left the organization.

But Rehm resisted the notion of drawing a connection between the furor over Williams and the mistake with Norris.

"I'm not sure in this instance that's fair," she said. "Michele was asked to be one of the main authors...she's one of the most important people at NPR."

Rehm said she hopes NPR can rectify the mistake with Norris in subsequent printings of the book.