The flipped classroom method has gained popularity in recent years with the idea that it is possible to use the time spent in classrooms more effectively by simply flipping the passive lecturing parts with the homework exercises. Accordingly, this article investigates the effectiveness of the flipped classroom in teaching grammar to EFL learners. A study was conducted with the participants of two English courses in a vocational school in Turkey. Results indicated that the flipped group achieved higher scores than the non-flipped group and that the difference between two groups was statistically significant. Hence, the factors that lie beneath this improvement are likely to be attributed to the teaching method, which is also supported by the answers given to a flipped classroom perception survey and a focus group interview.