Guided by post-structural perspectives of identities as processes of becoming and transculturation and transnationalism, this study explores how multilingual students in a Mandarin-English bilingual programme form their sense of identities in a dynamic process. Multiple forms of data are collected, including observations, interviews and documents. The findings indicate that multilingual students are mobile, namely, they move across linguistic, cultural and ethnic spaces of interaction. In addition, they challenge the dominant discourse of any fixed and hyphenated identity and take up transcultural and transnational identities that allow their comfortable circulation among different worlds. This study calls for a need to unfold children's multiple and mobile identities and explores new possibilities for life.