This introduction presents on overview of the key concepts covered in the subsequent chapters of this book. The book comprises essays from six decades of Nathan Glazer's remarkable career. The selection is by no means comprehensive; it could not be considering Glazer's prodigious output over this length of time. Instead, it is meant to be an introduction to what the authors find essential in Glazer's work and thought. They have organized the essays into sections corresponding to Glazer's wide-ranging interests: ethnicity, race, social policy, and urbanism and architecture. This is followed by a series of autobiographical essays Glazer has written over the years to explain the evolution of his own thought. Finally, Glazer's work has influenced succeeding generations of thinkers and scholars in a number of fields and the authors include at the end of the book appraisals and assessments by several of these writers.