This study investigates the role of prior grounding attained in mathematics in predicting the academic achievement of enrollees in Bachelor of Science in Actuarial Science (BSAS). The investigation is based on administrative records of 240 BSAS enrollees at Makerere University, School of Statistics and Planning in the 2007-2009 cohorts. Students' graduating Cumulative Grade Point Average (CGPA) was adopted as a measure of their academic achievement. Mathematics grade scores obtained by the students in their Advanced level (A-level) of secondary education were adopted as a measure of competence in the discipline. Academic achievement was modeled in the analysis by enrollees' characteristics and their competence in mathematics using a robust regression. The results revealed that students' CGPA increases with their A-level mathematics scores. A similar pattern is observed when the assessment is made using a combined weighted score of enrollees adopted on admission to the program. The findings confirm that 1) prior academic qualifications predict enrollees' academic achievement and 2) competence in A-level mathematics predicts success in the program.