Kazuo Yamaguchi is the Ralph Lewis Professor of Sociology at the University of Chicago, where he has served since 1991 in a variety of capacities including the chair of the Department of Sociology (2008-2011) and Hanna Holborn Gray Professor (2005-2013). He has also been a visiting fellow at the Research Institute of Economy, Trade and Industry (RIETI), Japan since 2003. He previously served as associate professor (1987-1991) and assistant professor (1985-1987) in the Department of Sociology, University of California-Los Angeles and assistant professor, School of Public Health, Columbia University (1983-1985). His research interests are in quantitative methodology, work and family, social stratification and social inequality, and theory of rational/purpose social action. His recent research focus is on gender inequality in Japan. He was also the Institution for Scientific Information (ISI)'s most frequently cited scholar in the social sciences during 1980-1999.