The Book of Daniel was published in 1971 when Doctorow was a Visiting Author at the University of California, Irvine.
Doctorow conceived of the idea for the novel in the late 1960s - an era of intense conflicts over Vietnam, the Civil Rights Movement, and social change. In an interview, he explained how his interest was piqued: "Out of the...campuses came something called the new left, and I began to wonder how it compared with the old left of the 30s. It occurred to me that I could tell the story of this country's life over a 30-year period by dealing with its dissidents. And I realized that the Rosenbergs could be the fulcrum. Everything snapped together." He has said numerous times that it is not about the Rosenbergs specifically, but the idea of them. The novel was a bit shaky getting started; it was not until Doctorow had his now-mythical epiphany that it started to take shape. He was “writing in the third person, and it wasn't working. I had this terrible moment when I threw 150 pages across the room and said 'If I can make this story dull, I don't have any business writing.' So I put a new sheet in the typewriter and began to write almost in mockery of my own ambition. It turned out to be page one. Having Daniel tell the story was a way of being intimate with everything that happened without understanding it. That was my position as the writer." Daniel's story bridges the gap between the left of the 1930s and the new left of the 1960s by recounting his childhood among the fictionalized version of the Rosenbergs and his current struggles with his sister and her idealism.
It was extremely well-reviewed and is generally considered the most accomplished work in Doctorow’s oeuvre. The New Republic review said it was “the political novel of our age... the best work of its kind,” while the Guardian described it as a “masterpiece” and the Chicago Tribune said that it was like reading a capsule history of the American left in the twentieth century... Public knowledge comes face to face with personal private pain, and the result is staggering.” Doctorow’s contemporary Joyce Carol Oates found it “a nearly perfect work of art, and art on this level can be only a cause for rejoicing.” It was nominated for the National Book Award. In 1983 the novel was adapted into a film entitled Daniel, directed by Sidney Lumet.