The majority of the world’s children grow up and receive education in multilingual societies, many being first introduced to literacy in a second language. Most reading science research, however, does not address the influence of linguistic diversity on literacy acquisition and tacitly assumes a scenario in which children learn to read in their mother tongue, spoken in a linguistically homogeneous community. We discuss some of the key issues regarding linguistic diversity, its effects on literacy acquisition and the challenges linguistically diverse societies experience in meeting the educational needs of their people. We use global adult literacy rates to explore the relationship between linguistic diversity and literacy by examining respective contributions of a country’s Language Diversity Index and its economic wealth (GNI per Capita) to its literacy rate. The results reveal significant independent contributions by both factors. We discuss the implications of these issues for literacy research.KeywordsMultilingual societiesLinguistic diversityLiteracy acquisition