This study investigated expressive writing in 8- to 10-year-old children with different levels of reading comprehension. Poor and good comprehenders were presented with three expressive writing tasks where the modality (pictorial vs. verbal) and the text genre (narrative vs. descriptive) varied. Results showed that poor comprehenders’ performance was minimally influenced by the modality of the prompt. In fact, their performance was generally worse than that of good comprehenders and affected by the text genre, as the quality of their narratives was generally lower than that of good comprehenders. However, in the descriptive text condition, their performance was comparable to that of good comprehenders. One can conclude that their problems depend on the characteristics of the narrative text where coherence and causality are important elements.