This study examines how novice foreign language (FL) writers develop their genre awareness, linguistic knowledge, and writing competence in a genre-based writing course that incorporates email-writing tasks. To define genre, the study draws on systemic functional linguistics (SFL) that sees language as a resource for making meaning in a particular context of use rather than as a set of fixed rules and structures (Halliday, 1994). To design genre-based syllabi that can promote both language and writing development, the study also attempts to link "genre to task" (Norris, 2009). In the fifteen-week writing course, Japanese undergraduate students (n = 70) engaged in carefully designed genre-based tasks, where they learned the ways in which different genres are shaped by different linguistic resources to achieve their goals through sequenced task phases. Three sets of qualitative and quantitative data were collected to examine students' changes as a FL writer: survey, interviews, and the emails written at the beginning and the end of the semester. The results showed that the students made progress in their genre awareness and perceptions, and that changes in their awareness were apparent in their actual written products. The study discusses that a combination of genre and task can create a crucial pedagogical link between socially situated writing performance and choices of language use, which is expected to serve as a springboard to create interfaces between writing and language development in FL contexts.