The document presents a study on code-switching among peers in a project-based English course at a Hong Kong university, focusing on how Chinese and English are used throughout different stages of project work. It highlights the role of language choice in fostering learner autonomy, teamwork, and problem-solving, while analyzing data collected from two participant teams. The study raises questions about the appropriateness of language switching in English instruction and the opportunities for independent language learning within project-based tasks.