The aim of this pilot study is to build a new computer-based test for the assessment of French-language vocabulary for primary school pupils. Multiple choice tasks measuring the extent (i.e., image) and depth of vocabulary (i.e., Synonyme, Definition) were given to 255 children. The speed and accuracy of the replies were recorded. As expected, the analyses revealed that the school level, gender and lexical frequency of items affected the correct response times and/or answers. Performance improves with school level and for frequent words. Girls seem to have a richer vocabulary than boys (e.g. depth) and seem less sensitive to the frequency of words than boys. An analysis of the psychometric qualities of the test resulted in a 36-item test with a satisfactory internal consistency. Finally, a confirmatory factor analysis did not reveal a two-factor structure of vocabulary (e.g. depth, extent). The results are discussed in terms of the quality of lexical representations and choice of tasks.