Error analysis was performed on the writings of 50 grade 12 & 13 students from 14 Fr-speaking schools in Ontario. Time allotted for writing on a choice of contemporary problems was 1 hour & 15 minutes. Students were not allowed to use either grammar book or dictionary. Average text length was 450 words. Error indices were computed for each student, for each grade, & for 3 student groups: those who plan to enroll in a higher learning institution, those who plan to find work immediately, & those without precise plans. Error %s were computed for the following lexical categories: preposition, V, article, adj, pronoun, & N. The highest %s occurred in the preposition & V categories. Number concordance errors were computed for V, adj, N, article, & personal pronoun, with the highest % of errors in the V & adj categories. Error type analysis indicated that lexical use, orthography, & number concordance accounted for 55% of total errors. It is concluded that a majority of students have a poor command of written Fr. Results are explained based on the poor diffusion of French in Ontario. A. Orianne