The Bologna Process has taken an undeniable role in the development of the European Higher Education Space to create a shared framework at the higher education level. In this new framework, teachers' and students' mobility is the key element. This is one of the main aims that European Union education policies try to achieve. This study is about the mobility of Erasmus and Sicue students in the European Union and the Spanish university context. It tries to explain mobility through three basic lines of research: documentary analysis, the application of eligibility index and work field. The methodology used gathers qualitative and quantitative data from a sample of Erasmus and Sicue students. The results show that the participation in a mobility programme is not only connected with a personal profile but also with other factors that can promote or inhibit this decision. The most important factors are related to the family and relationship context, the features of programmes and the promotion that takes place in the universities.