The hope of her grandmother, a servant in 1950s Mississippi, was that the young Oprah Winfrey would "get some good white folks" to work for, the star talk-show host recalled Saturday.

"I regret that she didn't live past 1963 and see that I did get some really good white folks — working for me," Winfrey told an estimated 30,000 people gathered for graduation ceremonies at Howard University, one of the nation's most prominent historically black universities.

Winfrey drew repeated big cheers from the moment she took the stage on the university's main quadrangle to address the 2,300 members of the class of 2007 — 50 years after the Rev. Martin Luther King Jr. spoke at Howard's commencement.

"I stand here as a symbol of what is possible when you believe in the dream of your own life," Winfrey said. "Don't be afraid. All you need to do is know who you are."

The 53-year-old, whose show has remained the top-rated talk show for 20 consecutive seasons, said her success comes from maintaining her principles and serving others.

"My integrity is not for sale, and neither is yours," Winfrey said, recalling times when she was under pressure to change course or avoid topics to help boost television ratings or keep advertisers. "Do not be a slave to any form of selling out."

Winfrey recalled how early in her career at a TV station in Baltimore, executives told her she was "too big" and "too black" and "too emotional." She said they tried to have her TV name changed to "Susie" because it would be more familiar, but she refused. Finally Winfrey was put on a talk show, she said, to run out her contract.

"And that was the beginning of my story," she added.

Winfrey also spoke of what she called a crisis with the nation's black youth.

"They don't know what you know. They're falling and they're failing. They're dropping out at rates of 50 percent and higher because we, our generation, didn't teach them who they are," Winfrey said. "We have a responsibility to raise them up, to lift them up, to save them, to liberate them from themselves."

Hugh Duckett, 38, of Baltimore, graduated with his wife Diane Duckett. They both earned master's degrees in divinity and are associate ministers in Catonsville, Md.

"Oprah's speech was powerful," he said. "She showed us what our vision is and our call to give back — to be the men and women that God called us to be."

Mothers, fathers, sisters and cousins crowded onto the Howard University campus. Some 18,000 people sat on the quadrangle, while others filled the football stadium and 10 other sites on campus, university spokeswoman J.J. Pryor said.

Rhonda Williams traveled from Cleveland to see her 21-year-old daughter Ashley Williams graduate with an accounting degree. She said Winfrey's opening of an academy for girls in South Africa was inspiring for her as a teacher.

Winfrey was awarded an honorary doctorate in humanities for her generosity, which Howard President H. Patrick Swygert said "inspires all of us to grow."

"You see with a journalistic eye and intellect, but you tell the complete story with your heart," he told her.

The new degree drew calls of "Doctor Oprah" from the crowd.

When it came time for her to speak, Winfrey echoed African American studies scholar Henry Louis Gates, Jr., of Harvard University, who also was awarded an honorary degree Saturday.

"You can receive a lot of awards in your life. But there is nothing better" — she paused to wipe away tears — "there is nothing better than to be honored by your own."