This article focuses on the issue of retention in Greek higher education institutions. It is an issue of growing significance in the last decades, after the expansion of higher education and the increase in the number of university students. It is based on a literature review and the results of a research the aim of which was to investigate the factors to which students' attribute the fact that they have either not completed their studies in the period nominally expected for their study programme, or have withdrawn. Research data show that retention constitutes a complex social problem and that there is a relationship between retention and socioeconomic factors. We conclude that a full understanding of the issue, as well as efforts to increase student success presuppose the study of social parameters, which will examine the relationship between students' socioeconomic background and their studies, within each country's specific financial, social and cultural framework.