We know very little about the French vocabulary that is learned in school and this paper reports a study which measures learners' vocabulary size and progress in secondary school. The methodology for estimating vocabulary size in French is comparable with vocabulary size testing in other foreign languages, and this makes comparison with vocabulary learning in French and other languages possible. Results suggest that learners learn about 170 words per year up to GCSE and about 530 words per year in ‘A’ level study and are influenced by word frequency. On average, learners take GCSE with under 1000 words of French vocabulary and ‘A’ level with about 2000 words. These results appear modest compared with historical data and when compared with other language exams pitched at the same CEF levels as GCSE and ‘A’ level. Vocabulary size predicts ‘A’ level grade particularly impressively. There is a worrying period where progress, even of the best learners, appears to halt for several years.