This is a study on teachers' professional development through action research practice. The participants of the study were 23 English Language Teachers (ELT) who teach in high schools, preparatory schools and colleges in Debre Markos, in Dessie and around in 2014. The methods of data collection were teacher reflection, and in-depth interview. The ELT teachers felt that the Action Research (AR) involvement helped them develop their profession. Because of their involvement in the inquiry, they changed their perception of research and their role as teachers and researcher. Their interest towards action research develops as they do the research. Their consciousness about EFL teaching rises when they research on their own classroom and environment in relation to English language teaching. The teachers felt that AR brings opportunity especially for female teachers who have other responsibilities at home and in the surrounding. The teachers' perception shows that they are comfortable with doing action research. In-service action research is an economical, effective and efficient method of professional development. The teachers read and explore literature to enrich their research. This implies that some push factor should be there to break the silence of teachers who have developed comfort with what they have. Researching pushes teachers to read the academic literature, update themselves, write and contribute to the intellectual world by adding knowledge backed with experience and expertise.