This autoethnographic study reports on a team-teaching experience in a bilingual education class in Taiwan. For decades, governments in East Asia have promoted team teaching between a native English-speaking teacher (NEST) and a local teacher (LT) in English as a foreign language (EFL) classrooms. These programs are now expanding to include bilingual education academic subject classrooms. With this expansion, there is a need for scholarship to inform bilingual education team-teaching professional development (PD). The author, a NEST and teacher educator, collaborated with a science LT for a 4-week bilingual science unit. The purpose of the inquiry was to use the experience to propose a set of competencies to inform team-teaching PD. Data were collected through class video recordings, a reflective journal, and the LT's written reflection, which were analyzed through a lens of seven teacher competences. Despite both teachers' extensive knowledge and experience, the study revealed the need for skills within each competence unique to bilingual education collaborations. These findings were used to propose a set of ten competencies that may be used to guide PD for team teachers in bilingual education.