Linguistic plurality is a situation in which a speech community speaks more than one language. It is a complex sociolinguistic phenomenon that helps explain the complexity of human nature. Human beings cannot exist in isolation and are therefore inclined towards interaction and transaction. The need and desire to interact leads to language contact, where two or more languages co-exist and are constantly used by people who share definitive interests. Linguistic homogeneity is illusory, since there is hardly any linguistic community that is absolutely monolingual. Despite the complexity of linguistic diversity, the world has recorded tremendous developments in the arts, sciences, and technology. This highlights the strength that lies in diversity. The utilitarian nature of multilingualism can be explored for the growth and development of human society, as language is a key factor in development. Although multilingualism might pose a threat to nationalism, it is apparently the basis of nationhood in Nigeria, having existed even before colonization. The purpose of this paper is to explore the importance of linguistic plurality for sustainable development. This study uses a descriptive and qualitative methodology, heavily relying on the nativist theory and the framework of Role and Reference Grammar (RRG) as its major underpinnings. Drawing from these frameworks, the paper observes that language acquisition occurs naturally with the presence of the Language Acquisition Device (LAD), and consequently, languages are used to perform functional roles. The scope of this work is limited to multilingualism and sustainable development in Africa, with particular emphasis on Nigeria.