Corporations operating in America seem to be stagnating when it comes to improving racial diversity, the NAACP said Monday as it released report cards that measured 55 companies on their efforts.

Most companies' rankings were virtually the same as last year, an indication that some businesses are not making much effort to improve, said Dennis C. Hayes, interim president of the NAACP.

"The opportunities for African-Americans to participate in this American dream depends on all of us being included," Hayes said.

The report cards were released during the annual convention of the Baltimore-based National Association for the Advancement of Colored People, a six-day event that ends Thursday.

The companies included were in the telecommunications, lodging, finance, retail and auto industries. They self-reported their work with blacks in employment, charitable giving, advertising, contracting and community service.

Taken together, four industries got a C grade. Retail got a D, largely because five of the 11 companies examined did not respond to the NAACP's request for information. Those companies received Fs.

NAACP officials said that, in the future, the civil rights group may organize boycotts of companies that don't supply diversity information.

"We will no longer allow folks to just ignore this," said Nelson Rivers, chief operating officer for the NAACP. "It really is outrageous."

BellSouth (search) received the highest rank of all the companies, a 3.3 out of a possible four points. Blacks are well represented on its work force, including managers and board members, the NAACP report shows.

"We believe we have to go to many places to find talent -- we don't limit ourselves," said Valencia I. Adams, vice president of diversity at BellSouth Corp., based in Atlanta. "Once we bring (minorities) in, it's our belief that we have to provide a culture and environment for them to flourish and grow."

Among the companies that responded, Mitsubishi Motors North America got the lowest rank, a 1.18. The NAACP report said that the U.S. branch of the Japanese automaker had many of its black employees doing either clerical or administrative work. There were no blacks on the board of directors or in recruiting, and the company spends no money advertising with black media, the report said.

Mitsubishi spokesman Dan Irvin said he could not comment on the ranking because he had not seen the NAACP report, but said 40 percent of his company's charitable giving goes to the black community.

"MMNA is absolutely committed to diversity," Irvin said. "It's a part of our culture. It's a part of who we are."

The NAACP first began compiling the report cards in 1996, when it probed the hotel industry for diversity issues following complaints that blacks received unfair treatment. Next year, they may add more categories, such as oil and gas, Rivers said.

Also at the convention, U.S. Sen. Barack Obama, an Illinois Democrat, called for reauthorization of the Voting Rights Act (search), which expires in 2007, and actor Harry Belafonte received an award in recognition of his social justice work.