Liechtenstein has one of the highest foreigner quotas in Europe while simultaneously pursuing a very restrictive naturalization policy. This is problematic from a state-political perspective, as a large part of the population cannot participate in democratic decision-making. The reasons why naturalization in Liechtenstein has not been facilitated more than before, and has even been made more difficult recently, can be explained not only by political fluctuations but also by the history of naturalization. This history has been explored by Klaus Biedermann, Nicole Schwalbach, Veronika Marxer, and Regula Argast in a research project supported by the Historical Association for the Principality of Liechtenstein over several years. The present final report summarizes the research findings and discusses the relationship between continuity and disruption of naturalization in Liechtenstein since the 19th century.