This paper compares the learning gain over one year of schooling among 15-year-old students in Austria and Scotland (United Kingdom). Common metrics for reading, mathematics and science learning, as established by the Programme for International Student Assessment (PISA), are used. In order to overcome the limitations of a cross-sectional, single-cohort design, multiple cycles of PISA data are combined. The fact that Austria and Scotland moved their testing period across cycles is also exploited. The results are used to establish a benchmark for other performance differences observed in PISA, such as gender gaps, socio-economic gaps or between-country differences.