His research deals with globalization, immigration, ethnicity and nationalism. He focuses on studying the effects of global changes in citizenship rules - especially the growing acceptance of multiple and non-resident citizenship - and their impact on the meaning of nationality. Harpaz uses a range of data and methods – original statistics, interviews and comparative-historical analysis – to explore the growth of a new relation to national membership which diverges from the traditional view of citizenship as a binding, exclusive tie to a specific nation-state. Harpaz earned his Ph.D. in Sociology from Princeton University in 2016. His work has been published in International Migration Review, Journal of Ethnic and Migration Studies and other publications.