Following the third wave of democratization, many scholars feared that the spread of democracy to ethnically divided societies would cause political instability and violent ethnic conflict (See, e.g., Collier 2009; Reynolds 2011). Rosenblum (2007: 29) observes how ‘the working assumption in democratic theory is that parties based on religious, ethnic, racial, or cultural identity are uniquely dangerous’. As mentioned by Bertrand and Haklai in the introduction to this volume, a range of institutional mechanisms has been proposed to address existing or potential ethnic conflict, with much attention focusing on the electoral system. Until recently, party regulation in general and party bans in particular received little attention in the literature on democratization and ethnic diversity. This is surprising, especially in light of the tendency towards the constitutionalizing of party democracy (Van Biezen 2012). In Africa, ethnic party bans are the norm. By 2009, only six countries did not have a ban on particularistic parties and the trend is towards more ethnic party bans (Moroff 2010a).1 Africa is by far the most active continent when it comes to the political engineering of political parties, at least on paper. Whereas in Western democracies prohibition of parties is a measure directed at extremist and undemocratic parties (Fox and Nolte 1995), in Africa there is a wide range of grounds on which parties are banned. The most important are brotherhood, clan, community, ethnicity, faith/religion, gender, language, region, race, sect, social condition/social or economic status; and tribe. At least four ‘targets’ of party bans can be identified: (1) party program; (2) party symbols; (3) party organization; (4) party membership. Party bans can be directed at any one of these aspects separately or in combination. To put ethnic party bans in perspective and to differentiate among them, it is helpful to think of two functions that parties can perform in a heterogeneous society. Broadly speaking, political parties can either articulate or aggregate ethnicity (Bogaards 2004b, 2007b, 2008). A political party that presents itself as the champion of one particular community is a good example of articulation. A political party that campaigns on a broad platform intended to appeal to voters from different ethnic backgrounds is a good example of aggregation. The term ‘blocking’ refers to situations where the constitution, electoral law, or law on political parties prohibit ethnic parties. Ethnic blocking is what we call here a

negative ethnic party ban. In contrast, a positive ethnic party ban provides incentives for national parties (aggregation). If aggregation is indeed a desirable property of the party system in a heterogeneous society – because it is associated with moderation and integration (Horowitz 2000; Reilly 2006) – then it is crucial to know how aggregation can be promoted through the electoral system and party regulation. Two core questions are addressed in this chapter. Do ethnic party bans help create national parties? Are positive party bans better suited for creating national parties than negative party bans? This study is novel in at least three ways. First, with the exception of Elischer (2008, 2013), no analysis of party nationalization in Africa has taken place. While party nationalization scores have been calculated for many other regions around the world, no such data are available for Africa. We therefore have a unique, albeit still highly incomplete dataset. Second, the literature on party regulation has so far neglected Africa. Drawing on a collaborative research project on Ethnic Party Bans in Africa, we are in the fortunate position to have access to data on ethnic party bans in the whole of Sub-Saharan Africa.2 Third, party regulation has not so far been examined as a potential influence on party nationalization scores. Although there is an increasingly sophisticated literature on the determinants of party nationalization, the effect of spatial distribution requirements has not been taken into account.