This study examines how immigrants in the European Union adapt to their neighboring host countries. We analyze Estonians in Finland, the country’s largest group of foreign nationals, with surveys of 2398 adult Estonians, covering six per cent of this population. Finnish-language proficiency, intermarriage with Finns, and raising children in Finland strongly predict Estonians’ deeper adaptation and matter more than duration of residence. After many years in Finland, Estonians’ adaptation trajectories have diverged: only a small minority are fully adapted, and even fewer remain fully separate from the Finnish society. Despite Estonians’ having linguistic proximity and familiarity with local norms in Finland, their active online interaction and frequent visits to Estonia sustain belonging to their country of origin, moderating and slowing progress toward full adaptation. Domain-specific lens better captures variation in adaptation than a single overall score: partial adaptation of the majority of Estonians unfolds differently across accommodation, employment, and free-time social life.