This article reports on two quasi-experimental studies that investigated the possible development and transfer of audience awareness in novice EFL writers as they engaged in online writing tasks through a Social Networking Service (SNS). Japanese students from two universities were asked to write, read, and comment on other students' writing once a week. The two studies were arranged sequentially so as to capture in an exploratory but jointly illuminating manner whether and how the "elusive" (Hyland, 2005) construct of "sense of audience" can develop and transfer across genres. The results of both studies suggest that the SNS environment can help L2 writers develop audience awareness and transfer that awareness across genres when two conditions are met: (1) the genre of the SNS tasks should be perceived as similar to that for which transfer was expected; and (2) the students did not develop a sense of audience in previous writing instruction.