In light of known challenges in the transition from school to university in mathematics, we investigate differences in the (mathematical) prerequisites of mathematics majors and preservice mathematics teachers. Results show that although there are no significant differences in high school grade point average, mathematical prerequisites of mathematics majors are significantly better than those of preservice mathematics teachers. Differences are higher in conceptual than in procedural knowledge with medium effect sizes between mathematics majors and preservice higher secondary teachers and (very) large effect sizes between mathematics majors and preservice lower secondary or primary school teachers. These results are discussed regarding transition challenges and the fit of prerequisites and chosen study program.