Death At An Early Age, a description of his first year as a teacher, was published in 1967 and received the 1968 National Book Award in Science, Philosophy, and Religion. Now regarded as a classic by educators, Death At An Early Age sold more than two million copies in the United States and abroad.

After being fired from his first job, Kozol did a short teaching stint at a suburban school. The shock of going from one of the country's poorest public schools to one of its richest never left him. From the start, Kozol combined teaching with activism. He taught at South Boston High during the city’s desegregation crisis. Working with black and Hispanic parents, he helped set up a storefront learning center that became a model for many others throughout the U.S. In 1980, the Cleveland Public Library asked him to design a literacy plan for the nation’s large cities. His plan became the model for a major effort sparked by the State Library of California. The book that followed, Illiterate America, was the center of a campaign to spur state, federal, and private action on adult literacy.

A few days before Christmas 1985, Kozol spent an evening at a homeless shelter in New York. Nightlong conversations with the mothers and children who befriended him led him to remain there for much of the winter. Out of that experience came Rachel and Her Children: Homeless Families in America, a narrative portrayal of the day-to-day life struggle of some of the poorest people in America. The book was presented to state governors by homeless advocacy groups. Kozol gave them his full support and founded The Fund for the Homeless, a non-profit organization that provides homeless families with emergency assistance. The book received the Robert F. Kennedy Book Award for 1989 and The Conscience in Media Award of the American Society of Journalists and Authors.

In 1989, Kozol revisited America’s schools. He went to rich and poor schools in over 30 communities. This experience led him to write Savage Inequalities: Children in America’s Schools (1991), which received The New England Book Award in non-fiction.

In 1993, Kozol journeyed to the South Bronx. Two years of conversations with the children, clergy, and parents who befriended him led to the writing of Amazing Grace: The Lives of Children and the Conscience of a Nation, published in October 1995. The book explores the lives of some black and Hispanic children whom, although they live in one of the most violent, diseased communities in the developed world, retain a soaring spiritual transcendence. Despite the severe political conservatism of the 1990s, Amazing Grace became a national best-seller within three weeks of publication. Amazing Grace received the Anisfield-Wolf Book Award in 1996.

In a stirring departure from his earlier work, Kozol has published Ordinary Resurrections (May 2000). Like Amazing Grace, this work also takes place in the South Bronx; but it is a markedly different book—we see life this time through the eyes of children, not, as the author puts it, from the perspective of a grown-up man encumbered with a Harvard education. A work of guarded optimism that avoids polemic and the fevered ideologies of partisan debate, Ordinary Resurrections is about the persistent innocence of children who are still unsoiled by the world and can still view their place in it without cynicism or despair.

His newest book, The Shame of the Nation: The Restoration of Apartheid Schooling in America, released in September 2005, quickly became a national bestseller by utilizing Kozol's masterful overview of the public school system delivering an informed and poignant analysis of the inequities along race and class lines.

A summa cum laude graduate of Harvard and a Rhodes Scholar, today Kozol lives in Massachusetts.