Professor Mesthrie is the research chair in the School of African & Gender Studies, Anthropology & Linguistics (AXL). He is a past president of the Linguistics Society of Southern Africa (2001-2009) and a past head of the Linguistics Section at UCT (1998-2009). He was elected honorary life executive member of the Linguistics Society of Southern Africa in 2012. He is currently an executive member of the International Society for English Linguistics and an elected member of the SA Academy of Science. He has published widely in the field of Sociolinguistics, with special reference to language contact and variation in South Africa.