This paper discusses multidimensional aspects of identity formation in a European context, referring to Polish migrants’ experiences of migration in Belfast, Northern Ireland. Its aim is to understand the dynamics inherent in the process of identity construction by exploring the incidence of multiple ethnic identities among Polish nationals. To this end, following theoretical consideration on a sense of belonging and boundary making mechanisms in contemporary societies, it examines the incidence of Polish, local, European and cosmopolitan identities among migrants. It then points out at contradictions between different layers of belonging and explores the situations in which they occur. The paper draws on the findings of a one year long ethnographic fieldwork and uses the results of participant observation and in-depth interviews.