The aim is to better understand acculturation starting from the preparatory stage of the immigration process. The research focuses on two understudied groups of skilled voluntary migrants preparing their move to Finland: ethnic migrants from Russia and international employees recruited to the European Chemicals Agency from EU member states. As studies on pre-acculturation are still rather scarce, both previous acculturation and expatriate literature are applied and completed with social psychological theories of intergroup relations and organizational psychology. The results of the research indicate that immigrant acculturation is a complex process that begins already at the pre-migration stage and involves at least four different dimensions of pre-migration adaptation. The results point to the crucial role of early contact experiences of potential migrants with future home country nationals. According to the results, it is essential to identify the expectations and beliefs related to potential migrants' pre-acculturation orientations and pre-migration adaptation, including stress reactions prior to migration. Moreover, the results speak to the importance of psychological resources and preparedness for a successful pre-acculturation. The research emphasizes that pre-acculturation should be given more attention in both acculturation and expatriate literature, as intervention at the pre-migration stage is likely to give the best outcomes by promoting the most adaptive acculturation profiles.