Despite recent attempts made worldwide to address the language and pedagogical needs of non-native English teachers through in-service teacher training programs, little empirical research exists as to how effective such programs are in terms of improving English teachers’ language proficiency and teaching skills. The purpose of the study is to provide a holistic evaluation of an in-service teacher training program by assessing proficiency gains between the pre-test and the post-test as well as tracing on-going development of teaching skills through process-oriented procedures. In addition, the participants’ self-perceived evaluation of the program and their self-report on changes in language proficiency, comfort level, and teaching skills are presented. The comparison of the pre-test and post-test reveals that the participants improved their English proficiency. Development in teaching skills was also observed, and other important gains including increased overall teaching competence,