This study aims to analyze Korean EFL graduate students’ writing strategies as mediated actions in their semester- long process of L2 research paper writing using multiple resources including the Internet. Though the study was based on the sociocultural approach, it analyzed mediated writing strategies quantitatively and qualitatively. The participants’ writing processes were video-recorded; their use of the computer was recorded through a keystroke logging program; their writing strategies and resource uses were inquired by using strategy and resource use inventory questionnaires and logs and conducting retrospective recall interviews. Results of the study revealed that the students shared certain writing strategies as actions mediated by resource types, the target writing genre and readers, the language used for writing, and cultural background, as well as the purpose of writing behaviors across writing stages. They also illustrated individual variations: their mediated actions were interwoven with individual goals and beliefs, learning styles and habits, personalities, self-regulation, educational experiences and backgrounds, experiences of academic writing including research paper writing, disciplinary knowledge, and availability of resources, in addition to their L2 proficiency, such as writing skills and confidence in L2. Findings from the study imply that L2 writers deploy diverse mediated actions in academic writing which are rooted in socioculturally and academically situated individual contexts.