WASHINGTON — President Obama spoke in unusually personal terms at the White House on Thursday about how he got high as a teenager and was at times indifferent to school as he deplored what he called America’s numbness to the plight of young black men.

Drawing on the power of his own racial identity in a way he seldom does as president, Mr. Obama sought to connect his personal narrative about growing up without a father to that of a generation of black youth in the United States who he said faced higher odds of failure than their peers.

“I didn’t have a dad in the house,” Mr. Obama said as he announced a $200 million, five-year initiative, My Brother’s Keeper, to help black youth. “And I was angry about it, even though I didn’t necessarily realize it at the time. I made bad choices. I got high without always thinking about the harm that it could do. I didn’t always take school as seriously as I should have. I made excuses. Sometimes I sold myself short.”

Mr. Obama said the idea for My Brother’s Keeper occurred to him in the aftermath of the killing of Trayvon Martin, the Florida teenager whose death two years ago sparked a roiling national debate about race and class. He called the challenge of ensuring success for young men of color a “moral issue for our country” as he ticked off the statistics: black boys who are more likely to be suspended from school, less likely to be able to read, and almost certain to encounter the criminal justice system as either a perpetrator or a victim.