[Tesis ini menjelaskan belief yang diyakini oleh pengajar Bahasa Inggris di dua institusi yang berbeda. Dalam setiap proses mengajar, para pengajar memiliki belief (keyakinan) yang memengaruhi keputusan mengenai praktik pembelajaran serta memengaruhi kegiatan yang dilakukan oleh pengajar tersebut di dalam kelas. Untuk keperluan pelatihan pengajar ke arah yang lebih profesional, oleh sebab itu meneliti hubungan belief dan praktik pengajaran dinilai menjadi hal yang penting. Tesis ini menggunakan kuesioner BALLI untuk menginvestigasi belief yang diyakini oleh pengajar. Pengajar diwawancarai untuk menggali informasi mengenai belief yang diyakini lebih dalam. Observasi yang dilakukan terhadap dua orang pengajar dinilai telah mampu mewakili data yang diperoleh mengenai hubungan belief dalam praktik pengajaran yang dilakukan di kelas. Hasil penelitian menunjukkan bahwa belief pengajar di sekolah formal dan nonformal terdapat perbedaan. Seluruh pengajar menunjukkan belief yang positif mengenai Bahasa Inggris dan praktik pengajaran yang dilakukan akan tetapi dalam hubungannya dengan praktik pengajaran yang dilakukan, pengajar sekolah nonformal lebih menunjukkan belief yang diyakini dibandingkan dengan pengajar di sekolah formal. Ada beberapa faktor yang memengaruhi adanya perbedaan antara belief yang diyakini dengan praktik pengajaran yang dilakukan. Faktor-faktor tersebut adalah kondisi kelas, karakteristik pelajar, dan materi pembelajaran;This thesis describes the belief of teachers at two different institutions. In every process of teaching, teachers have a belief that influences the decisions about instructional practices and the activities carried out in the classroom. For the purposes of teacher training towards professionalism, therefore studying the relationship between beliefs and teaching practice is considered to be important. This thesis uses BALLI Questionnaire to investigate teachers‟ beliefs. After that, teachers are interviewed to gain deeper information about their beliefs. Observations done of two teachers are considered to be adequate in representing the data about the relationship between beliefs and teaching practices in the classroom. The result of the research shows that beliefs of teachers in formal and non-formal school are different. All teachers show positive responses of belief about English and teaching practice, unfortunately formal school teachers fail to reflect their beliefs into teaching practices. There are several factors which affect the difference between beliefs of the teacher and their teaching practices. Those factors are the condition of the class, the characteristics of the students and the learning materialsBelief, This thesis describes the belief of teachers at two different institutions. In every process of teaching, teachers have a belief that influences the decisions about instructional practices and the activities carried out in the classroom. For the purposes of teacher training towards professionalism, therefore studying the relationship between beliefs and teaching practice is considered to be important. This thesis uses BALLI Questionnaire to investigate teachers‟ beliefs. After that, teachers are interviewed to gain deeper information about their beliefs. Observations done of two teachers are considered to be adequate in representing the data about the relationship between beliefs and teaching practices in the classroom. The result of the research shows that beliefs of teachers in formal and non-formal school are different. All teachers show positive responses of belief about English and teaching practice, unfortunately formal school teachers fail to reflect their beliefs into teaching practices. There are several factors which affect the difference between beliefs of the teacher and their teaching practices. Those factors are the condition of the class, the characteristics of the students and the learning materialsBelief]