Stefano Gallo deals with the social history of contemporary Italy, with experience in researching archival sources and documents ranging from the end of the 19th century to the 1980s. He has more than 100 research products to his credit, including books, articles, essays and reviews, and 50 participations in and organization of scientific conferences and seminars.

His main fields of research are the history of migration and the history of work. He teaches "History of migration in the contemporary age" at the Department of Civilization and Forms of Knowledge of the University of Pisa (specialist degree course in Contemporary History). His latest book is entitled "History of work in contemporary Italy" (il Mulino 2023, with Fabrizio Loreto).

He helped found the Italian Society of the History of Work, of which he was the first coordinating secretary until 2015 (storialavoro.it). Since 2021 he has been scientific director of the Franco Serantini Library - Historical Institute of the Resistance of the province of Pisa. He is also a member of the doctoral board of the Research Doctorate in Social and Political Change, an international and interdisciplinary Doctorate of excellence of the Universities of Turin and Florence.