My research centres around different aspects of bilingualism and multilingualism, including the acquisition of multiple languages in childhood, family language policy, education policy and practice regarding bilingual and multilingual learners of minoritized and transnational backgrounds, complementary schools, cognitive benefits of language learning, and impact of on social cognition and creativity. I am currently leading a project 'Early Childhood Bilingualism: Effects on brain structure and function' (Leverhulme, 2018-2021), with colleagues in the Great Ormond Street Hospital Institute of Child Health. I was co-investigator on a large AHRC project ‘Translation and translanguaging: Investigating linguistic and cultural transformations in superdiverse wards in four UK cities, (£1,973,527, 2014-18. AH/L007096/1) with colleagues in Birmingham, Birkbeck, Cardiff and Leeds until 2018 and an ESRC project 'Family Language Policy: A multi-level investigation of multilingual practices in transnational Families' until 2020), with colleagues in Birkbeck and Bath. Between 1988 and 2000, I was involved in three consecutive ESRC-funded research projects on language maintenance and choice in the Chinese community in Tyneside in the North East of England. In 2006-8, I worked on another ESRC-funded project on multilingual practices of complementary schools in England (RES-000-23-1180), with colleagues in Birmingham, East London and King's College London. I was CI for the ESRC seminar series ‘The Multilingual University: The Impact of Linguistic Diversity in Higher Education in English-dominant and English Medium Instructional Settings’ (ES/M00175X/1). I have also been involved other research projects on grammatical profiling of normally developing and speech disordered young English-speaking children (Nuffield Foundation) and reliability of identification and referral of speech and communication disorders in young non-standard or non-native English-speaking children (ESRC).