We study the reproduction and change of participatory political culture by examining how immigrants' political engagement develops in the cross-pressure between their country of residence and their ancestral country. To explain patterns of political (re)socialization, we suggest a mechanism of proximity-conditioned social diffusion, which stipulates that immigrants' retention and adoption of a given participatory culture is a function of spatial and temporal proximity to native bearers of this culture, from which diffusion occurs. Analyzing the political participation of thousands of first and second generation immigrants in the European Social Survey (2002–2018), we find that immigrants come to adopt the participatory culture of their new country and lose that of their ancestral country through a symmetrical temporal process: having stayed longer in the destination country—either being a second generation immigrant or a first generation immigrant, who lived there longer—they adopt this participatory culture more strongly, while at the same time loosening their connection to the culture of the ancestral country. Spatial proximity to natives also conditions immigrants' adoption of the prevailing culture of the destination country as immigrants’ participatory inclinations resemble that of natives in their residential regions within the destination country.