Postgraduate students’ Life Satisfaction (LS) has been few explored, in a context where mobility towards universities abroad is increasing. In Luxembourg, more than half of students pursue their studies in a different country, and must be able to cope with this transition. Our research questions were (1) which factors are associated with students’ LS, according to their country of studies, and in relation to their mental health, career attitude and socioeconomic characteristics? and (2) which determinants contribute to a better LS for each group? For the years 2012 and 2013, all postgraduates who had obtained a financial aid from the Luxembourgish government were contacted by post to complete an online questionnaire. For the 492 respondents, the regression analysis showed that a higher health satisfaction leads to higher LS. Career optimism and planning were positively associated with LS for students in Luxembourg. Higher were autonomy and career adaptability, and lower was worry, better was the LS for those studying in EU. To enhance students’ LS, it is suggested a preparation for a successful mobility organized by the corresponding CEDIES of every country. Moreover, an accompaniment realized by the hosting university should be also proposed to students in mobility.