How do you build theory based on empirical research? What is the relationship between theory and data collection, and how does it vary across disciplines? What is the difference between theory-building and theory-testing? What kinds of ‘theory’ are relevant for particular kinds of research? In this session, we bring together three scholars working across disciplines on a range of exciting empirical issues. Prof. Federico Varese, sociologist who works on mafias; Dr Martha Newson, an anthropologist who works on group bonding including among football fans; and Prof Andrea Ruggeri, whose work focuses on civil wars, political violence and peace operations.