Lesson Study is a professional development method involving a group of teachers working collaboratively towards a jointly prepared research lesson. The purpose of this study is to apply Lesson Study in the English as a Foreign Language context of Turkey. The participants are three English instructors and 18 students in the English Preparatory Program at a Turkish university. The instructors prepared a research lesson, and the lesson was presented by one of the instructors while the other instructors were observing students. Following the first lesson, a post-lesson discussion among the instructors was carried out, and students filled out an open-ended survey about the lesson. After necessary revisions were made in line with the participants’ suggestions, the lesson was presented to another group of learners at the same level, and the opinions of students and teachers about the revised lesson were collected once again. The analysis of the qualitative data obtained from students revealed that Lesson Study led to the improvement of the research lesson. Moreover, it was found that Lesson Study was considered beneficial by the instructors as a means of professional development.