Researchers working on the effects of study abroad are always baffled by the huge individual differences in the development of a target language (TL) among students - who could be considered as temporary immigrants (Kinginger 2011; Regan et al. 2009). Researchers often speculate that these differences are linked to socialization issues, such as the amount of authentic TL interactions that students engage in. What research designs usually lack are the unique psychological characteristics that could predict the frequency with which L2 users' engage in L2 interactions. The present study investigates this question by looking at the link between personality traits and frequency of use of English L2 as well as self-perceived proficiency in English L2 by 102 adult Polish immigrants living in Ireland and the UK. Participants filled out a Polish version of personality questionnaires (OCEAN and TEIQ) and a sociobiographical questionnaire. Statistical analyses revealed that length of stay was positively correlated with English L2 use and self-perceived proficiency in that language. Linear regression analyses revealed that Openness and Self-esteem were significant predictors of frequency of use of English L2. Openness was the best predictor of self-perceived English L2 proficiency. In sum, these results suggest that progress in the L2 depends not just on the immersion in the L2 but also on the L2 user's basic inclination to seek out social interactions in the L2.