The Rev. Bernice King and Martin Luther King III were joined by his wife, Arndrea, who is expecting the couple's first child in May. The three placed a wreath at the tomb where Dr. King and his wife, Coretta Scott King, are buried.
Afterward, the three held hands and prayed for several moments, then posed for photographs for the crowd and media. About an hour later, Bernice King addressed about 2,000 students at nearby Ebenezer Baptist Church -- where her father preached from 1960 until his death -- and urged them to pick up her father's cause.
"You have been chosen for greatness," she told the applauding students. "You have to step up to the plate and represent for your generation."
Speaking for about 30 minutes, the Rev. King shared her own troubled youth as an example to the students, telling them that they could break the cycles of their broken backgrounds to make a difference.
"For a season in my life, that bullet caused an explosion of hate, anger and rage in my own heart," said the Rev. King, who said she wrestled with feelings of condemnation and revenge.
Understanding her father's teachings and seeing her mother's example in the decades after his death helped her to get past those emotions, she said -- though she acknowledged she still struggles today.
"I am engaged in a daily battle," she said.
Her remarks were part of the 40th anniversary youth commemorative service, led by King lieutenant Bernard LaFayette Jr., who directs the Center for Nonviolence and Peace Studies at the University of Rhode Island.
"They tried to assassinate his dream," Mr. LaFayette told the overflow crowd. "You have come here today 40 years later to say that they missed. You are here to make sure that the next generation does not destroy itself in violence."
Most in the audience raised their hands when asked whether they knew someone in jail or who had dropped out of school. The students took a pledge to incorporate principles of nonviolence into their lives and to teach the lessons to other young people.
Bernice King and Martin Luther King III were expected to travel to Memphis, Tenn., on Friday to lay a wreath at the Lorraine Motel where their father was killed April 4, 1968.