The research project presented in this article was set in the Swedish school context and carried out on a set of compulsory national tests for English, Swedish, and mathematics used at the end of compulsory school. The aims were: (a) to gain a deeper knowledge of the internal structure of the tests and (b) to separate individual performance from school performance. Individual test results from a representative sample of approximately 30% of the cohort (n = 26,360) constituted the data. Factor analysis, of a basically confirmatory nature, was applied in the study. Modelling at the individual level resulted in a theoretically sound, 11-factor model demonstrating good fit. The corresponding analyses at the school level, using 2-level structural equation modelling techniques, generated a similar, although somewhat less complex, model. Approximately 12% of the total variation in performance on the tests proved to be associated with schools. (Contains 4 tables and 4 figures.)