This study examined how French third (36) and fifth (36) graders used the morphosyntactic context when they spell morphologically complex words with homophonous suffixes (/a/). Participants had to spell adverbs (/a/ transcribed ent) and present participles (/a/ transcribed ant), contrasted on the basis of their frequency, in isolation or embedded within a sentence. Spelling performances were better when the words were dictated in the context of a sentence than in a condition of isolated word dictation. This was the case even in Grade 3, despite the fact that explicit teaching about the transcription of the suffixes /a/ had been provided only to the fifth graders. The frequency of target words was an important determinant of spelling success even when a sentence context was provided. Thus, even though children benefited from the morphosyntactic information provided by the sentence, they did not rely (systematically) on a morphological rule such as "words ending with /a/ are always given the ant spelling after the preposition en (e.g., en regardant "in looking")."