The purpose of this study was to investigate how two Japanese teachers used the target language (Japanese) and students’ first language (English) in a college-level, beginning Japanese course. Although the ACTFL (American Council on the Teaching of Foreign Languages) recommends “extensive use of the target language,” most research studies focus on European languages. Data collection was conducted in a large Midwestern University, including classroom observations, semi-structured interviews, and questionnaires. Qualitative analysis revealed Japanese teachers used both Japanese and English but as students learned more Japanese, they increasingly communicated in Japanese. The mix of Japanese and English were related to environmental factors, teaching styles, and personalities. Pedagogical decisions were not solely based on optimizing students’ learning; the survival of the Japanese program was also paramount in pedagogical decision-making. Students positively perceived their experience of learning Japanese and considered both teachers’ use of languages as optimal, despite their radically different approaches. The classroom was a complex system consisting of manifold variables, including negotiated co-adaptations, which promoted language learning.