In this work we set out to investigate the feasibility of applying measures of lexical frequency to the assessment of the writing of learners of French. A system developed for analysing the lexical knowledge of learners, according to their productive use of high and low frequency words (Laufer and Nation 1995), was adapted for French and used to analyse learners’ texts from an Open University French course. Whilst we found that this analysis could not be said to reflect the state of the learners’ vocabulary knowledge in the same way that Laufer and Nation’s study did, elements of the system’s output did correlate significantly with scores awarded by human markers for vocabulary use in these texts. This suggests that the approach could be used for self-assessment. However, the feedback that can be given to learners on the basis of the current analysis is very limited. Nevertheless, the approach has the potential for refinement and when enhanced with information derived from successive cohorts of learners performing similar writing tasks, could be a first step in the development of a viable aid for learners evaluating their own writing.