Richard Alba is distinguished professor of sociology at the Graduate Center of the City University of New York. His most recent book, coauthored with Nancy Foner, is 'Strangers No More.' Kenneth Prewitt is the Carnegie Professor at Columbia University, president of the American Academy of Political and Social Science, past director of the Census Bureau, and author of 'What Is Your Race? The Census and Our Flawed Effort to Classify Americans.' Tom Kecskemethy is the executive director of the American Association of Political and Social Science.