As Finnish university admissions are reformed, more information is needed on the relationship between performance in prior education and later academic achievement. Transition to university is a critical period, and low performance in prior education is associated with challenges in later study. In the present study, law students' (n = 426) performance in the National Matriculation Examination was investigated in relation to later academic achievement at university. Quantitative methods were used. Findings showed that prior performance was not only associated with study success but also with study progress. The results also showed that law students who had grades in the advanced mathematics course were faster and more successful at university. This work contributes to the existing knowledge of university admissions ahead of the Finnish reform by providing new insights into prior performance and how it is related to academic achievement at university.