In light of growing demands for English language proficiency, the Ministry of Education, Culture, Science, Sports, and Technology of Japan (MEXT) promulgated educational reforms that enabled public elementary schools to launch English education ("English Activities") in 2002. Public elementary school teachers in Japan are not certified to teach English; thus, the government has extended its support by inviting native speakers of English to assist elementary school teachers. The Ministry's effort to promote English education, however, has raised some questions: "Who is better qualified to teach, homeroom teachers or native English speakers? How would they collaborate if they had to teach together?"

This dissertation documents one public elementary school's implementation of a collaborative EFL teaching model with a focused examination of the native speaking (NS) and nonnative speaking (NNS) teacher-student discourse and interactional styles in the classroom. The study compiles three smaller studies that investigates (1) teachers' perceptions about NS and NNS teachers' English proficiency and their teaching abilities, and students' perceptions about learning from NS and NNS English teachers; (2) NS and NNS English teachers' classroom discourse and interaction with students in relation to the teachers' roles and expectations, and how NS and NNS teachers' discourse and interaction with students influence their English language learning; and (3) the roles and functions of teacher planning sessions and their contribution to collaborative EFL teaching, respectively.

The research employed a mixed-method approach, adapting an ethnographic perspective to classroom studies. Through classroom observations, interviews, and surveys conducted with 4^th, 5^th, and 6^th grade elementary school students, and their teachers, the study found that teachers' power relations, roles and responsibilities, and their own perceptions toward English language education shaped their classroom discourse in ways that made their teaching styles in the collaborative teaching model distinct and unique from one another. The findings also show that students see positive benefits in learning English from both NS and NNS English teachers, but believe that the presence of a bilingual teacher is a necessary and critical component in English language education program. The study presents policy and practice implications for the implementation of future English language education programs.