This paper surveys the use of instruments of direct democracy, such as the referendum and citizens’ initiative, to settle issues of contested sovereignty in divided societies. Our focus is on a cluster of cases where the politics of direct democracy has been associated with separatist dynamics. This includes cases such as the disintegration of the former Soviet Union and Yugoslavia, as well as more contemporary cases such as Catalonia, Scotland and South Sudan. We contrast various types of dynamics, distinguishing in particular between consensual referendums (e.g. Scotland’s 2014 independence referendum) and unilaterally staged referendums (e.g. Catalonia’s 2014 independence referendum). We also place the contemporary phenomenon within its broader macro historical context. Our overall aim is to investigate the conditions under which self-determination referendums may be conducive to conflict resolution and when instead they are associated with the escalation of ethno-national conflict.