This chapter summarizes current research on differences between racial or ethnic groups and national cultural groups on predictors that are frequently used in employee selection. It reviews the research on score differences for African-American, US Hispanic/Latinos and Whites, as well as national culture groups, examines the various explanations for those differences and propose directions for future research aimed at further understanding score differences between groups. Before investigating the research on observed score differences, it is important to highlight the scope of the covered predictors and the difference between constructs and methods in the predictors commonly used in personnel selection. Current research finds that minority cultural groups tend to score lower on cognitive tests than the majority cultural group. As was true for the research on score differences between race and ethnic groups, aspects of the measurement can play a role in differences observed.