Studies of student re-enrolment patterns in Higher Education constitute, along with traditional studies of persistence and dropout, a key element for improving the quality of Higher Education Institutions. However, these studies tend to be limited as they are centred on a single institution, due to the lack of national-scale datasets for monitoring students between different institutions. Using a longitudinal population-based dataset provided by the Catalan University Assurance Agency (AQU), which includes information records on 21,473 undergraduate students, this paper aims to develop and test an exploratory model of student re-enrolment, specifically, in the Catalan public university system. We are not only interested in student re-enrolment, but also in whether they do so during the first year after dropout or in the same area of knowledge. Results from logistic regression analysis revealed that although most students return to the university system in the first year after dropout, many of these change to a different area of knowledge, which is clear evidence of dysfunctional and inefficient guidance systems and university entrance. Findings provide a more accurate and complete picture of student re-enrolment behaviour and suggest the need to develop targeted policies to improve the efficiency and effectiveness of our university systems.