This study theoretically and empirically addresses the interrelationship between transnationalism and second-language proficiency as a crucial aspect of integration in the first years after immigration. Attention is paid to country of origin engagement and distinguishes and tests such engagement in economic, political, social and cultural domains simultaneously as well as exploring it over time. Opposing hypotheses are formulated on the association between such engagement and Dutch language proficiency among recent Polish and Turkish migrants using assimilationist theory, offering a perspective still prevalent in societal debates, and transnational theory, proposed as an alternative to the former in previous studies. Three waves of panel data of the New Immigrants Survey Netherlands enabled studying migrants’ initial level of Dutch language proficiency after migration as well as recent migrants’ development herein. Neither assimilationist nor transnational theory finds support, suggesting that country of origin engagement matters little for recent migrants’ (development of) Dutch language proficiency.