Much of the research on ethnoracial diversity in nonmetropolitan America consists of case studies describing how the arrival of Hispanics has transformed a particular community. To complement this work, we examine the dimensions and sources of diversity for a sample of 10,000 nonmetro places. Two dimensions of diversity—magnitude and structure—are identified, and hypotheses about their changes and correlates are drawn from the spatial assimilation and locational persistence perspectives and relevant scholarship. Our analysis of 1990–2010 decennial census and American Community Survey data documents a pervasive upward trend in diversity magnitude. However, places tend to follow parallel rather than identical diversity trajectories and to retain the same type of racial-ethnic structure in 2010 that they exhibited 20 years earlier. Fixed effects regression models show that ethnoracial diversity gains are most likely in nonmetro communities with plentiful economic opportunities, fewer old residents, and growing total, foreign-born, and correctional populations. These correlates hold for micropolitan and rural places and across census regions. Though our results largely conform to locational persistence logic, we find that spatial assimilation still has some merit, underscoring the importance of incorporating multiple theoretical models in a segmented change perspective on nonmetropolitan diversity.