English has played a major role in today’s society, due to the process of globalization and internationalization. It has become the language of academia and language of higher education. Due to its widespread and use, higher education institutions have started to organize courses in English to attract students worldwide. Erasmus, as the largest mobility programme, offers students to use English in academic and informal context. The aim of this study is to show international students’ opinion and use on their English development skills during Erasmus mobility programme. It investigates which context was more beneficial to their perceived language improvement, formal setting or informal setting. Results of this study imply that students perceive time spent during Erasmus mobility programme as linguistically valuable. The findings suggest that students depict out of classroom use of English more useful to their English improvement, than in-class experience. Small number of participants, uneven number of undergraduate, graduate and postgraduate students and students’ accountability affect the overall findings of this study. Further research is recommended to assess students’ English proficiency and skill development before and after Erasmus mobility programme in and out of classroom in order to get insight into the English language development in non-English speaking countries during Erasmus.