This paper argues the case of linguistic relativity through a Vygotskyan socio-cultural perspective. A major tenet of Vygotskyan socio-cultural theory is that sign systems (e.g., language) are psychological tools, which after a period of internalization, result in a transformation of inner processing. The logical extension of Vygotskyan socio-cultural theory is that the internalization of different sign systems, such as Chinese logographic characters or English alphabetic script, should invariably result in the development of distinct types of inner processing. This argument is essentially one of linguistic relativity, or the idea that the nature of language itself can impact on cognitive processing. Evidence to support this argument is found in behavioural and neuroanatomical studies. Finally, some implications to ESL pedagogy are discussed within a relativist framework.