摘要：AbstractWith the phenomenal spread of English as global lingua franca, the need for a mastery of this language for educational and/or professional purposes has heightened. English as a foreign language (EFL) and English as a second language (ESL) programs now emphasize the students’ development skills, especially in L2 English writing. This study aimed at finding out the effect of two writing types, namely, narrative and cause - effect, on fluency, complexity and accuracy of Iranian EFL learners’ writing across proficiency. Based on a placement test, 60 participants out of 100 learners were randomly selected based on their proficiency and assigned into two groups (i.e., intermediate and advanced, 30 learners in each group).All the participants wrote 2 argumentative compositions individually in 2 subsequent sessions. in order to find out the possible effects of each activity on fluency, complexity and accuracy, the researchers analyzed the compositions quantitatively through a series of two- way analysis of variance (ANOVA) .The results were significant in the measures of complexity and fluency in T - unit numbers but not in accuracy and fluency regarding word number and clause number across proficiency.
