Kadir Nelson is at an enviable point in a brilliant career. Two-time Caldecott Honoree, he is the go-to illustrator for an array of Hollywood stars with picture book projects—Will Smith, Spike Lee, Debbie Allen. He's worked on films with Steven Spielberg, designed an album cover for Michael Jackson, and a stamp for the U.S. Postal Service. His best-known work—emotionally powerful portraits of larger-than-life figures from history—hangs on museum walls from Yokohama to Washington, D.C., to Bristol, England. But for an artist who can pretty much call his own shots, Nelson certainly did not take the easiest way out with his current project, his most ambitious yet: writing and illustrating a history of the African-American experience.

"I signed it up on the basis of about a page and a half of beautifully crafted text," says Donna Bray, who published Nelson's We Are the Ship at Hyperion before becoming co-publisher at HarperCollins's Balzer + Bray imprint. "I was at once really impressed and completely terrified, but the bottom line was: I trust Kadir."

Three years later the dividend of that trust is Heart and Soul: The Story of American and African Americans (HarperCollins/Balzer + Bray, Aug.) which PW, in a starred review, called "a tremendous achievement." In the voice of a woman who's seen it all, Nelson takes readers from pre-Revolutionary War America all the way up to the election of President Barack Obama, recording the tragedies and the triumphs.

"It's ironic," Nelson writes in his author's note. "History was not at all my favorite subject in school." And yet much of the acclaim that has come Nelson's way stems from his ability to powerfully illuminate the troubled existence of blacks in America—the perilous journey out of slavery in Henry's Freedom Box, written by Ellen Levine; the soul-stirring biography of Harriet Tubman in Carol Boston Weatherford's Moses; the indignities suffered by the men who played baseball just as well as white men but were paid a pittance because of the color of their skin in We Are the Ship. "I had been telling the African-American story all along but I hadn't tried to tell it all in one place," Nelson says.

Before We Are the Ship, he hadn't written the stories himself either. The success of that book, which won the Coretta Scott King Author Award and the Robert F. Seibert Medal (for nonfiction), gave him the confidence to try again, albeit on a much broader canvas. When Bray gave the green light, however, he remembers thinking, "Uh-oh. This is a big fine mess I have gotten myself into." Nelson confided his fears to a friend who confirmed them. "He said to me, ‘There's no way you can do that! It's too big! Do you know how many books you're going to have to read?' He was just saying what I had already said to myself."

Nelson was determined, however. "Someone once asked me what my work was about and I said, ‘I am in hot pursuit of the truth.' History is a way to look for it. You get a general swath of it in school but that wasn't enough for me. I wanted to know the real story. And I had to begin with me. Find out more about my family, how they contributed not only to my life but to the life of our country."

Nelson persevered through several attempts that were "not good," he says now. He showed his draft to his agent, Steven Malk at Writers House, "who said to me, ‘Well. There's some good things here.' "Nelson took his struggle to Ann Dieble, the designer who had worked with him on We Are the Ship, which is narrated by a (fictional) old-time veteran ballplayer. In Heart and Soul he had tried a similar device—but the voice was less a person than "an ancient spirit from across the ocean." According to Nelson, Dieble told him, "Make it a woman. Don't go so far back in time."

"When she said that, I knew it was right. I immediately thought of my grandmother," Nelson says. His grandmother, Verlee Gunter-Moore, had inspired him before. A grocery store owner in Atlantic City, N.J., Gunter-Moore had muscular forearms from ripping up boxes by hand and shelving products. Nelson had used her as a model for Moses, as a "cuter version" of the powerfully built Harriet Tubman.

He also relied on family for research, interviewing siblings, his parents, aunts and uncles, his grandmother. He remembered a story his Aunt Elaine had once told him about the last member of their family to have been a slave. He prohibited the serving of black-eyed peas on New Year's Day, a Southern tradition thought to bring good luck, because when he was a boy, the black-eyed peas were poured into a horse trough on New Year's Day for the slaves on the plantation to eat like animals. "After he was freed, he vowed neither he nor any of his families would ever eat black-eyed peas on New Year's Day again," Nelson says.

His research traced his ancestors' path through American history. Who was the first to cross the Mason-Dixon Line to escape Jim Crow? Who served in a segregated military? Who sat at a whites-only lunch counter? Heard Martin Luther King Jr. speak in their hometown? "I began to see the roots and the branches of our family tree as they extended through American history. It was a really intimate way to learn our country's story."

For Bray, Nelson's way of channeling his research into a storyteller's voice makes the history go down easy. "It's so accessible," she says. "The work he puts into talking to people about their relationship to these historical events personalizes it in a way no textbook could. It's as if, through this elderly woman, the reader is being told, ‘Come. Sit down and hear a story.' "

And then there is Nelson's artwork—Africans, manacled and crowded on the deck of a ship, black soldiers on a battlefield literally fighting for their freedom during the Civil War, two women in winter coats walking, rather than riding the bus, in Montgomery, Ala.—which forcefully conveys the uphill struggle of blacks in America through the centuries. Nelson, who began drawing at the age of three, painting in oils at 16, and went to Pratt on an art scholarship, has spent a lifetime getting to this point.

"I think his work is more emotionally charged than anybody else's I've come across because he feels these subjects completely," Bray says. "So many of his portraits are composed so that the subject is looking directly at you. You feel so drawn in, like he's gotten inside these people. I think the reason for that is Kadir has not only passion for the subjects but compassion. He is moved by these stories and wants other people to feel the same."

Yes, Nelson says, he could choose lighter or easier subjects at this point in his career, but he feels drawn to take on subjects worthy of his considerable—and he would humbly say—natural-born talent. His next project is a picture-book biography of Nelson Mandela for Katherine Tegen Books at HarperCollins, for fall 2012.

"Some people don't discover what their gift is for a long time but mine was apparent from a very young age and I am cognizant of that and respectful and grateful," Nelson says. "It took a long time for me to figure out not to get in the way of it, that it's not really mine, it just comes through me. The only important thing about the work now is that I do whatever it is that is on my heart."