OCCASIONALLY, a scholar writes a book that greatly affects our understanding of the world. William Julius Wilson’s The Truly Disadvantaged: The Inner City, the Underclass, and Public Policy, published by the University of Chicago Press last year, is a work of this order. Wilson’s description of the black ghetto underclass, his analyses of the causes of their increasing misery, and his proposed solutions have led many to reconsider their interpretations of the phenomena he discusses. Wilson’s book has been praised by many policymakers and academies, including Michael Harrington, who characterized it as a “pathbreaking book, critically important to our current public and political debate as well as to social theory.”