The transition from secondary to tertiary education varies from country to country. In many countries, secondary school is concluded with high-stakes, national exams, or high-stakes entry tests are used for admissions to tertiary education. In other countries, secondary-school grade point average (GPA) is the determining factor. In the Netherlands, both play a role. With administrative data of close to 180,000 students, we investigated whether national exam scores or secondary school GPA was a better predictor of tertiary first-year retention. For both university education and higher professional education, secondary school GPA was the better prediction of retention, to the extent that national exams did not explain any additional variance. Moreover, for students who failed their exam, being held back by the secondary school for an additional year and entering tertiary education one year later, GPA in the year of failure remained as predictive as for students who had passed their exams and started tertiary education immediately. National exam scores, on the other hand, had no predictive value at all for these students. It is concluded that secondary school GPA measures aspects of student performance that is not included in high-stakes national exams, but that are predictive of subsequent success in tertiary education.