Much of the literature on ethnicity in Africa regards ethnicity as a central cleavage and associates its politicisation with civil war and deteriorating socio-economic conditions. Tanzanian society is not structured by this cleavage, making it an outlier among African states. Despite the negative impact of politicised ethnicity, little is known of the circumstances through which it germinates and comes to have negative consequences, or how it can be suppressed in Africa. The present article attempts a comprehensive analysis of the structural and historical factors that have made the move away from politicisation of ethnicity in Tanzania possible. It provides an eclectic structural and historical explanation that attributes lack of ethnic salience in Tanzanian politics to a particular ethnic structure, to certain colonial administrative and economic approaches, and to a sustained nation-building ethos. The argument results from a critical analysis of secondary material on ethnicity and the politics of Tanzania.