ABSTRACT This study investigated the ways in which different writing tasks influence the quality and quantity of FL composition, as well as the writing strategies used by American college students when composing in Japanese as a foreign language. The purposes of the study were three-fold: (a) to compare qualitative and quantitative differences between descriptive and narrative writing tasks; (b) to describe linguistic and rhetorical requirements in each task; and (c) to identify the discourse strategies utilized in the tasks. Three types of text analyses demonstrated that the two tasks posed varying linguistic and cognitive requirements. This finding suggests that different linguistic competencies are required to perform varying writing tasks. The data also indicated that narrative discourse involves more demanding linguistic processing, at varying levels, than descriptive discourse. In addition, the analyses demonstrated that the ability to expand and elaborate preceding subtopics in discourse accounts, at least in part, for individual differences in FL composition aptitude. This ability, moreover, is related to knowledge of content-word meanings. These findings are consistent with those from reading comprehension research, both in L1 and L2, and thus support the view that reading and writing involve essentially similar processes of constructing meaning.