ABSTRACT What can public attitudes towards the integration of co-ethnic migrants teach us about social integration in newly diverse societies? Research finds that South Koreans prefer co-ethnic migrants from culturally similar or desirable origins, but it says little about the integration of migrant groups. Existing data and qualitative studies suggest considerable barriers to fully incorporating otherwise preferred migrants. Focusing on integrating North Korean migrants in South Korea – a relatively privileged migrant group that enjoys substantial resettlement support but encounters barriers to full integration – this paper addresses the research gap by testing competing explanations of migrant incorporation. Informed by Intergroup Threat Theory (ITT), the study examines how threats defined as realistic or symbolic shape native attitudes toward these migrants. Using a conjoint survey experiment to measure preferences for economic, political, and social integration, we find South Koreans favor North Korean migrants with extended residence in South Korea, which is a marker for diminishing realistic and symbolic intergroup threats. Conversely, migrants signaling stronger affiliations to North Korea or lacking diverse social ties in South Korea fail to alleviate intergroup threat concerns and consequently face discrimination. Our findings offer insights into integration policy and contribute to the migration and citizenship literature and contemporary Korean Studies.