Following his early interests in land tenure and agricultural geography, deriving from his PhD on the land reform of Southern Italy, Russell's research interests shifted to the study of migration, which he has been researching now for 35 years. He has directed major research projects on return migration to Southern Italy (funded by ESRC), Irish migration (Trinity Trust and the Bank of Ireland), British retirement migration to the Mediterranean (ESRC), Albanian migration (Leverhulme Trust), international student migration (HEFCE) and second-generation return migration to Greece and Cyprus (AHRC). He also headed the Sussex involvement in the EU Framework Six Network of Excellence on 'International Migration, Integration and Social Cohesion in Europe' (IMISCOE). His main regional interests are in Southern Europe and the Mediterranean, but he has also researched migration, as a global phenomenon, in other parts of the world. He is a strong believer in the value of collaborative, comparative and interdisciplinary research, and in the integration of qualitative and quantitative methods.