David B. Grusky is professor of sociology and director of the Center for the Study of Poverty and Inequality at Stanford University. His books include Social Stratification: Class, Race, and Gender in Sociological Perspective; Mobility and Inequality: Frontiers of Research in Sociology and Economics; and Poverty and Inequality. Szonja Szelenyi has taught at Stanford University, The University of Wisconsin, and Cornell University. She is the author of Equality by Design.