This research concerns the transformation of one migrant community. It is based on an analysis of selected documents presenting Polish migrant associations in the Netherlands from the beginning of 1950s until the 1990s. The study offers an analysis of the minority mobilization process, with a focus on migrant organizational agency. It is a case study devoted to the Polish community in Eindhoven and its association, which was a local branch of migrant organization operating at a national level. The main sources used in the study are archival records, including organizational statute, circulars, information leaflets, press releases, official and private correspondence, bulletins, protocols, organizational reports, official declarations, and minutes from meetings. In addition, interviews and biographical data are taken into account. Most of the written sources were obtained from the archive of Franciszek Łyskawa, a Polish migrant soldier who settled in Eindhoven shortly after World War II. Over the course of the following decades, he remained an active member of the diaspora while also integrating into the host society, and he became a Dutch citizen. The study shows the evolution of this Polish migrant community from the precarious situation of the early postwar years through the development of immigrants’ associations and institutions which emerged in parallel to efforts to integrate into the multicultural society in the 1960s and 1970s and eventually the gradual decline of activity among the members of this community as immigrants.