This study aimed at investigating whether applying pre-writing strategies would affect the quality of L2 learners' compositions. Twenty three adult EFL students from Jahad-e-Daneshgahi English centre in Iran participated in this study. They were randomly assigned to control and experimental groups, including 11 and 12 participants in each. They were at the advanced proficiency level. Each student wrote five argumentative essays. Students in experimental group were treated to perform three pre-writing activities alternatively (concept map, reading relevant texts, and negotiation). The findings revealed that students wrote better compositions as a result of applying pre-writing strategies. Significant differences in two groups indicated that pre-writing activities had significant effect on the participants' writing achievement. The findings may have implications for English learners, English teachers and material developers.