This book provides an overview of an action research model which utilizes the Common European Framework of Reference for Languages (CEFR) and stresses the importance of systematically researching classroom practice. It introduces the complementary nature of the CEFR and action research, the CEFR, and the CEFR-focused Action Research Model (CARM). The book includes seven case studies guided by the model and concludes with an overall assessment of the efficacy of the CARM as a way to facilitate action research into CEFR-informed practice. Undertaken in a Japanese educational context, the focus of the book is squarely on classroom-based CEFR-focused action research concerning issues that all educators face, such as course design, materials development/selection, classroom implementation, learner autonomy and assessment.