Scholars debate the degree to which ethnicity—or a sense of belonging to an ethnic group—plays a role in African politics, with some going so far as to argue that certain African elections are a mere “ethnic census.” However, nobody disputes that ethnicity is an important factor in electoral politics, with a transition to multiparty politics across much of the subcontinent from the early 1990s having made ethnic cleavages even more conspicuous. This chapter reviews existing scholarship and considers the following questions: What is ethnic politics? Why is ethnic politics so widespread? And how can we understand variations in the level of ethnic politics? In order to understand why politicians might want to use ethnic identity for electoral mobilization, we need to weigh the appeal of ethnicity vis-à-vis other modes of electoral mobilization and their limitations. One of the main reasons why scholars expect African politicians to mobilize along ethnic lines is the perceived scarcity of viable alternatives; the bulk of the literature suggests that ethnicity matters to voters, especially in information-poor contexts, because it sends signals about which politicians and parties will advance their needs and benefit their group, and which politicians are unlikely to do so. Other pieces of information that would allow voters to assess candidates’ expected performance in office are underdeveloped, underutilized, and often not credible. Yet, ethnic mobilization is not ubiquitous across Africa. The chapter will also discuss several factors that can help to explain the absence of ethnic politics—such as ethnic demography, strength of local leaders, and cross-cutting cleavages.