This study investigates the effects of the types of tasks and feedback on Korean adult EFL learners' fluency, accuracy, and complexity. A qualitative approach was also added to determine the perceptions that learners and teachers have about task-based instruction (TBI) and feedback types with learning journals, interviews, and stimulated recall. Although the experiment had the limitations of a small size of subjects and short length, certain findings are worth noticing. For both levels of group learners (lower intermediate and higher intermediate), fluency was highest in the descriptive tasks receiving implicit feedback. For accuracy, the rate was highest when both groups performed descriptive tasks receiving explicit feedback. For complexity, only higher intermediate level learners showed substantially higher rates in narrative tasks with explicit feedback. Planning time and the freedom to choose the topic (picture to describe) presumably might have affected fluency and accuracy in descriptive tasks. Accuracy was found to have been more affected by explicit feedback that primarily provided corrections on morphosyntactic errors. In addition, the qualitative research on the perceptions that L2 learners and teacher had about their experience with TBI and feedback provides insightful perspectives that are hoped to contribute to designing more effective TBI and interactional corrective feedback. (201)