Refugees and diasporas are part and parcel of today’s accelerating global diversity and domestic diversity changes that we encounter in social interactions. These terms conjure up images in our mind of individuals who belong to certain social groups in host environments. Basically, their social identities define who they are and how they are treated by others in social interactions. While there is extensive research on refugees and diasporas in three separate but interrelated domains—refugee studies, diaspora studies, and immigrant studies, less scholarly attention has been paid to the conceptual distinctions between refugees and diasporas, among other things. The complexity of refugees and diasporas is explored along with some implications. Most studies are atheoretical in nature, and an intergroup perspective can provide insights into how they engage in identity negotiation and intergroup communication adaptation to host environments. Thus, a theoretical discussion is provided of how refugees and diasporas face the challenges to preserve, maintain, and further their distinctive social identities, and also adapt to the new environment by way of negotiating their social identity complexity using intergroup communication strategies.