"We study workplace segregation in the United States using a unique matched employer-employee data set that we have created. We present measures of workplace segregation by education and language--as skilled workers may be more complementary with other skilled workers than with unskilled workers--and by race and ethnicity, using simulation methods to measure segregation beyond what would occur randomly as workers are distributed across establishments. We also assess the role of education- and language-related skill differentials in generating workplace segregation by race and ethnicity, as skill is often correlated with race and ethnicity. Finally, we attempt to distinguish between segregation by skill based on general crowding of unskilled poor English speakers into a narrow set of jobs, and segregation based on common language for reasons such as complementarity among workers speaking the same language. Our results indicate that there is considerable segregation by education and language in the workplace. Racial segregation in the workplace is of the same order of magnitude as education segregation, and segregation between Hispanics and whites is larger yet. Only a tiny portion of racial segregation in the workplace is driven by education differences between blacks and whites, but a substantial fraction of ethnic segregation in the workplace can be attributed to differences in language proficiency"--National Bureau of Economic Research web site.