This study used quantitative analyses complemented by the retrospective data obtained through a stimulated recall procedure to address three interrelated issues: (a) whether second language learners use online planning opportunities to carefully plan their speech to enhance the quality of the language they produce, (b) what kinds of self-repair behaviour the pressured and careful online planning conditions are likely to induce speakers to make, and (c) the way careful online planning affects EFL learners' oral L2 performance as measured in terms of complexity, accuracy, and fluency. Thirty intermediate EFL learners were asked to perform an oral narrative task under careful and pressured online planning conditions. Results of the qualitative and quantitative analyses revealed that L2 learners use the planning time to monitor their speech for grammatical accuracy, to retrieve and monitor the appropriate lexical items, and to plan the message they will communicate. In addition, it was found that careful online planning conditions induce learners to execute more error repairs and fewer appropriacy and different-information repairs compared to the pressured online planning condition. An analysis in terms of complexity, accuracy, and fluency measures testified to the positive effects of careful online planning on L2 oral performance.