Structural equation modeling (SEM) depicts one of the most salient research methods across a variety of disciplines, including educational management. Recent research advocates the use of partial least squares structural equation modeling (PLS-SEM) as an attractive tool in action research. The purpose of this paper is to systematically examine how PLS-SEM has been applied in action research with the aim of investigating the effect of teacher’s leadership styles (transformational and transaction) and student’s motivational factors (intrinsic and extrinsic) on student engagement for implementation of Communicative Language Teaching (CLT) in classrooms as well as explore the mediating role of motivational factors of student between the relationship of teacher’s leadership styles and student engagement. A cross-sectional survey design was used for the study featuring a self-administrated questionnaire among the students of some selected schools in Bangladesh. The transactional leadership style of teachers influences student engagement, intrinsic, and extrinsic motivation while the transformational leadership style of teachers influences the intrinsic and extrinsic motivation of the student. Both motivational factors mediated the relationship between leadership styles and student engagement. This study contributes to the literature by providing teachers with the updated guidelines for action research by using PLS-SEM. The study also suggests the way for increasing student engagement for CLT implementation in classrooms.