The present study sought to investigate the effects of Summary Writing (SW), Picture Writing (PW), and Topic Writing (TW) tasks on the accuracy and complexity of Iranian intermediate EFL learners' writing performance. To this end, of 61 students majoring English Literature in Golestan University, Gorgan, Iran, 43 (10 males, 33 females) of them were considered homogenous as intermediate learners. The participants were then randomly divided into three groups of SW, PW, and TW receiving six 60-minute sessions of instruction covering five units of "Improve Your IELTS Writing Skills" (McCarter & Whitby, 2014). With respect to the accuracy of writing productions, the results revealed that intervention was effective and reached the significance level, and the results of post hoc test illustrated that SW outperformed both TW and PW and that TW had a better performance than PW. Regarding the complexity of writing products, it was revealed that instruction was effective and statistically significant. The results of post hoc test demonstrated that SW had the best performance compared to PW and TW although no difference was found between PW and TW. Subsequently, the paper discusses implications for learners and teachers and suggests some avenues for further research.