Action research has been used in EFL pedagogy for about thirty years. This book attempts to pull together the hitherto experience of scholars and teachers in using action research to enhance the effectiveness of teaching English as a foreign language. The first part of the book discusses action research in historical and social contexts, including the advancements in educational thought in the second half of the 20* century. It also provides an in-depth overview of adaptations of action research to the field of EFL pedagogy. Based on these theoretical considerations, the second part of the book presents the results of an analysis of 128 action research articles published worldwide, aimed at shedding light on the actual practice of action research, including the pre-empirical, empirical, and post-empirical stages of action research. Additionally, an evaluation of an action research module incorporated into a course in EFL didactics provides information about the effectiveness of individual components of the module and the transfer of knowledge and skills the students attained into other areas of study. The book is the first such broad attempt to synthesise theory and practice of action research in the field of EFL pedagogy. It may prove of interest to students, foreign language teachers, teacher educators and scholars.