This study examines the roles of English in Nigeria in terms of nation-building in the era of globalization. From historical and contemporary perspectives, the pride of place that English has in Nigeria is not incidental. Given its position on the world stage, the language is highly recognized in the country. It links the country with other nations of the world in the quest for knowledge, innovations and cross-domain development. In this regard, communication is the fundamental pillar of the sustainable growth and development of Third World countries including Nigeria. Fostering nation-building in a mulilingual, multi-ethnic and multicultural region like Nigeria inevitably involves deploying language policy frameworks that put into consideration, how English can co-exist peacefully and productively with Nigeria’s ethnography; in spite of the positive roles that language plays in a heterogeneous nation, it has divisive potentials that should be properly managed for the good of any nation. The parameters for the co-existence of English with Nigerian languages remain intriguing due to ethnic resentments. This paper hinges on two theoretical frameworks: Orisawayi’s Development Theory and Morgan’s Speech Community Theory. While the former highlights feature of development that any country is expected to aspire for, and acquire, the latter emphasizes not only the significance of shared system of communication in a speech community, but also the instrumentality of a global language to a forward-looking speech community. The paper concludes that English fosters nation-building in Nigeria because as a global language, it guarantees national cohesion, enhances social mobilization, its vocabulary stock is wide and the language is a medium of instruction in schools.