Reports on a study on how English-as-a-Second/Foreign-Language (ESL/EFL) writers use their first language (L1) when composing their second language and how L1 use is affected by second language proficiency and writing tasks. Chinese EFL learners were asked to compose aloud on two tasks--narration and argumentation. Analyses of their think-aloud protocols revealed that these student writers had both their first and second language at their disposal when composing in their L2. (Author/VWL)