This introductory article discusses comparative approaches and research topics explored by contributors to the issue’s special section “Comparing Arab Diasporas.” The article reassesses debates about early meanings of the term diaspora that reveal the potentials of comparative research in the study of diasporas. The article also reviews the body of contemporary work on diasporas and its use of comparative analytical approaches. It discusses in more detail the contributions to this special section with regard to major topics in the field of comparative diaspora studies, including the complex relations between diasporas and host countries, their majority populations, and the identity politics involved in these processes. Based on the case studies assembled in this special section, the article contrasts internal divisions in the Hadhrami and Syro-Lebanese diasporas, their institutionalization in formal organizations, and the role of trade in their integration into host societies and examines how relations to their homelands changed over time. Finally, the article pays special attention to Hadhrami and Syro-Lebanese diasporas after 9/11, analyzing forms of othering, discrimination, and stereotyping in various (inter)national and local contexts. By comparing the Hadhrami and Syro-Lebanese cases located in the Americas and Southeast Asia, this introductory article traces the spread of the global war on terror to different corners of the world and thus demonstrates how this war became a genuine “global” military and ideological venture.