The current study compared the effectiveness of recasts which triggered learners' modification to their incorrect forms with recasts which triggered no modified output. To this end, 60 Iranian EFL learners randomly selected from two EFL classes received recasts for their errors during task-based interactions with their interlocutors. Using a tailor-made design, we compared the efficacy of recasts which were followed by learners' modified output with the efficacy of recasts which triggered no modified output. The results indicated that recasts which were followed by learners' modified output were more effective than recasts which prompted no modified output on promoting L2 development.