The purpose of this study was to address a writing teacher's perspective about integrating Facebook, a social networking site, into a university-level English writing course in Taiwan. Data, including interviews with the teacher and class postings on Facebook, were analyzed inductively, qualitatively, and interpretively, resulting in three emerging themes about the Facebook usage: students' participation, the connection between class and Facebook discussion, and the affordance of Facebook. Each theme's underlying properties were identified. This study provides language instructors with insights into the adoption of Facebook in an EFL context and supports them to better design tasks on Facebook.