Research focuses on social change and social problems in the United States and Europe. He has written on inequality, education, poverty, demography, politics, and religion. His work on the statistical analysis of categorical data contributed to the development of standard models of social mobility patterns. He is co-PI on the General Social Survey, a major NSF-funded project begun in 1972 to collect data on social and cultural trends in the United States. His current projects include using tax and census records to estimate social mobility rates and the Academy's Lincoln Project, a panel addressing funding issues for the nation's public research universities.