After the destruction of the Polish state by the invading Nazi and Soviet armies in the autumn of 1939, about 30,000 Polish nationals fled to eastern Lithuania. This article examines the relationship between population displacement and ethnic rivalry in Lithuania at the onset of the Second World War. As ‘war victims’ in need of help and protection, over time these Polish refugees became increasingly ‘ethnicised’, socially differentiated and isolated from Lithuanian society, and vilified as a potential political threat. Furthermore, the official decision to create a legal category of so-called ‘newcomers’ deprived those Poles who had settled in Vilnius between the wars of citizenship and residence rights in Lithuania. This policy inflated the number of ‘refugees’ to more than 100,000. Various other official measures, such as the creation of camps, forced labour schemes, deportations and repatriations, show how the government manipulated the refugee crisis for its own political purposes.