Writing in a second language (L2) is a challenging task. It is demanded in academic context and considered a lifetime skill. In Indonesia, writing is the most neglected skill in schools, resulting in low writing proficiency among university students. The aim of this study is: 1) to identify the writing process of Indonesian EFL proficient student writers; and 2) to explore the writing strategies used by Indonesian EFL proficient student writers. Williams' writing process model was used as the basis for identifying the writing process, while Leki, Sasaki and Mu's writing categories were used to identify the writing strategies. This study used the qualitative case study research design integrating four data collection methods, that was, observation, interview, think-aloud protocol and video-stimulated recall interview. The results show that the student writers undertake a five-step writing process: prewriting, planning, drafting, pausing and reading and revising and editing, utilising 10 writing strategies: mechanics of writing; relating the topic to past experience and knowledge; talk-writing; freewriting; outlining; listing; using online materials; seeking help; taking the reader into consideration; and text organisation in each stage of the writing process. The study significantly contributes to the body of knowledge on writing, helps L2 writing teachers and L2 learners at all levels of writing using the model of the writing process and the proposed writing strategies.