This main purpose of this paper is to investigate the impact of task complexity on L2 learners' written narratives. It is argued that L2 learners' written performance is influenced by the complexity of task regarding accuracy, fluency, and complexity. 52 Iranian English learners were selected as the participants of the study. They were asked to write two narratives based on two different picture stories. First, they performed the here-and-now task (present tense and context-supported) and then, they performed the there-and-then task (past tense and context-unsupported). Next, the written narratives were coded to measure the accuracy, fluency, and complexity. The results of this study demonstrated that cognitively more demanding tasks were more fluent and no significant effects on written narratives were observed on measures of accuracy and complexity.