Nigeria is a multi-ethnic and culturally diverse society that has witnessed conflicts arising from this ethnic and cultural diversity. This paper expounds such conceptual issues as ethnicity, cultural diversity, federalism and national integration and then presents the historical background to ethnic and cultural conflicts in Nigeria. It is argued that national integration in the Nigerian context has been an attempt to forge “unity in diversity”, seeking to wish away socio-cultural differences and imposing uniformity in spite of complex cultural diversity. This has created more conflict and posed obstacles to unity, peaceful co-existence, progress and stable development. It recommends that national integration and its benefits can be realized only with the development and entrenchment of a supportive public culture; understanding, respecting and tolerating differences occasioned by socio-cultural diversity; as well as the development of new institutions and mechanisms that address poverty, revenue allocation and other national issues peacefully. Keywords: Ethnic diversity, cultural diversity, conflict, national integration, Nigeria