Some have blamed development failures in sub-Saharan Africa on collective political action by ethnic groups. But a new working paper by Philip Keefer shows political parties, though a key vehicle for collective political action, don't necessarily represent collective ethnic interests. The author, using Afrobarometer survey data from 16 sub-Saharan African countries, compares survey respondents belonging to ethnic groups that cluster their support around particular parties to survey respondents who don't. One definition of clustering that should be most associated with the pursuit of collective ethnic interests links a single party to a single ethnic group. But only a quarter of survey respondents belong to groups that cluster in this way. Moreover, respondents from ethnic groups clustered in this way were not significantly more likely to express a partisan preference than other respondents. This is inconsistent with the claim that competition between political parties is based on credible commitments to improve the collective welfare of ethnic groups. On the contrary, being from ethnic groups that exhibit clustering has a smaller impact on whether respondents exhibit a partisan preference than factors associated with individually-targeted political appeals. For example, respondents who receive gifts (which appeal to individual, not collective, interests) are more likely to express a partisan preference than those from clustered ethnic groups. The paper argues that ethnic clustering, rather than being a cause of worsening development outcomes, could be a byproduct of other aspects of the political environment.