As an inquiry based model, Lesson Study highlights teacher professional development in the field of English language teaching by giving teachers the role of researchers in classrooms. Gaining widespread popularity in different educational contexts and holding a great promise as a model of professional development, the Lesson Study model forms a basis for the present study aiming to provide insights into how teacher development is structured through social context and collaboration between colleagues when involved in an inquiry process, and how that learning leads to perceptual changes in teachers' views of the model and changes in teaching practices. The results suggest that the teachers had a positive attitude towards practice both at the beginning and at the end of the study. Although the teachers had initially some concerns before they actually experienced the model and it was their first experience with it, practicing the Lesson Study model seemed to meet their expectations, resulted in improvements in knowledge as well as teaching practices and perspectives, and made a contribution to personal and professional development with the help of engagement in professional collaboration, self-reflection, sharing of content knowledge and teaching experiences, peer observation, and critically discussing how to further enhance student learning.