Broadly speaking, Yongcan’s research is based on two sociocultural theoretical frameworks: (1) Lave and Wenger's Community of Practice (CoP) theory, focusing on the ideas of participation, distributed cognition and situated practice; (2) Vygotsky's Sociocultural Theory (SCT) of mind, which takes a socio-cognitive view and mainly deals with issues such as mediation, cognitive regulation and potential development. He brings together these two theoretical perspectives to understand the social nature and processes of second language teaching, learning and teacher development. Yongcan also has a long-standing interest in combining linguistic and social analysis in educational research. He has been involved in a series of linked projects on bilingual EAL children's language development, social integration and educational achievement. The findings of the EAL Assessment Project have been published as 'The EAL Assessment Framework for Schools', which is made available for all primary and secondary schools in England to assess bilingual children and to support teaching, planning and monitoring in schools. He is co-investigator of a flagship policy project on multilingualism funded by AHRC, crossing the disciplines of arts, literature, linguistics, education, neuroscience and health.