The impact of native and non-native English speaking teachers on students' learning English, as a foreign language has probably been an issue ever since English was taught internationally. The literature is rich and each group has its advocates and supporters. Some people believe that, for different reasons, only native English speaking teachers are able to teach English, while others think that bilingual teachers can be as effective as their colleagues, or even more. This book is response to this concern and aims at investigating the effect of Native English Speaking Teachers (NESTs) as well as Nonnative English Speaking Teachers (NNESTs) on students' achievement in speaking and writing skills and their attitudes towards English in the EFL classroom. This book is expected to fill a gap in the literature, which deals with the effective EFL teachers, and clarify the roles of both NESTs and NNESTs in language teaching. Secondly, it paves the way for more empirical research on the effectiveness of NNELTs, in the light of the findings of this research. Thirdly, the researcher hopes to provide policy makers and recruiters with some ideas about the best ways to hire EFL teachers