This study examines how blogs and their interactive and collaborative features help academically-advanced graduate students process academic writing knowledge and make sense of their writer identity. Seven graduate students undertaking Master's level study in TESOL and Linguistics participated. The research questions are: (a) What kinds of writing-related topics do students blog about? (b) How do students' collaborative dialogues on blogs help them process and reconstruct knowledge about academic writing? (c) How do students' collaborative dialogues on blogs facilitate their negotiation of academic identities and construction of authorship? Open-coding and content analysis were conducted to inductively identify salient themes and patterns regarding students' learning and perception of their writer identities. The results suggest that the blog activity not only encourages students to actively and reflectively engage in knowledge sharing, knowledge generation, and the development of numerous strategies to cope with difficulties encountered in the learning process. Blogs also endow students with a sense of authorship as the writers of blog entries and, at the same time, provide a space for them to sort out what being an author entails, their purposes of writing, and their authority in writing. (Contains 6 tables.)