Abstract：The present study investigated the effect of the Output Hypothesis on the way 30 pre-service ESL teachers interacted with learners and learners’ second language production. By controlling the order of teachers receiving training on the Output Hypothesis and participating in a communicative task, it was found that compared with teachers who received training after the communicative task, those who received training before the communicative task were more concerned with learners’ L2 output and asked more open-ended questions when talking with learners. Accordingly, learners who interacted with these teachers produced a larger amount of more complex L2 output. In addition, they noticed their own language problems and tested their own language hypotheses more frequently. This result shows that L2 teachers’ knowledge about the Output Hypothesis has a beneficial effect on their teaching practice.
