This study aims to evaluate a six-month domestic intensive English teacher training program (IETTP). It specifically examines what the participating teacher learners expected from the program, how they perceived its effectiveness. It also investigates how they developed in terms of linguistic and instructional skills through the program. Mixed methods were used to investigate 28 participants’ learning experiences in the program. The data include the program manuals, the participants’ pre- and post-test results, their surveys on the program and the courses, instructors’ feedback and evaluations on the teacher learners' microteachings, and the interviews with the program and academic coordinators. The results of the participants’ pre- and post-tests showed statistically significant improvement in their English skills except their speaking skills. In addition, the performance-based evaluation of their teaching demonstrations revealed their development in instructional skills. Overall, the teacher learners perceived that their language and teaching skills improved through the IETTP. However, some teacher learners suggested that more direct support should be made to improve the communication skills. This study provides important implications for teacher learners, teacher educators, and policy makers. (177 words)