There has been a growing interest in the influences on undergraduate performance in recent years as a result of the increasing diversity of students entering third-level education and an ever increasing emphasis on the development of a robust knowledge economy. This paper investigates the influence of students' dominant interest types and prior academic achievement on undergraduate performance in an Irish university. Holland's Self-Directed Search (SDS) interest inventory was completed by 308 students drawn from three, second year undergraduate programmes in engineering, nursing and teaching. The impact of dominant interest types and prior academic achievement on the performance of these students in their second year was then investigated using correlation and linear regression analyses. When combined, student interests and prior academic achievements were found to account for between 38% and 50% of the variance in undergraduate performance for students in these three undergraduate programmes.