International large-scale assessments (ILSAs) have become an important part of the Swedish evaluation system. It is therefore of crucial importance to validate national measures of Swedish students' achievement with their ILSA test scores. Here, we offer results from such a validation study based on Swedish students' test scores in IEA's Trends in International Mathematics and Science Study (TIMSS) 2015 in year 8, their final grades at year 9, and their national test grades at year 9. We find there is high consistency between what is measured in TIMSS and what is measured by indicators in the Swedish national assessment system.