This paper presents an excerpt from the results of research on the relationship between the experience of the legal and institutional environment by long-term Slavic migrants living in Poland and their acculturation process. It concentrates on the experience of citizenship and its connection to acculturation processes. Template analysis (TA) was conducted on data from (A) five in-depth expert interviews with migration professionals, (B) 20 biographical and narrative interviews with migrants from European Slavic countries who came to Poland between 1989 and 2010, and (C) legal and policy documents. The findings provide information about (A) migrants’perceived irrelevance of citizenship, (B) their perceived importance of citizenship, (C) the presence of formal and informal barriers to accessing citizenship status, and (D) the sense of obligation that citizenship evokes. The research argues that it is unjustified to treat citizenship uncritically as the main indicator of the effects of the acculturation process or only as an instrument that inevitably supports this process.