Abstract: A common view of contemporary African societies is that they are primarily tribally oriented and that state-based nationalism is incredibly weak, especially among cultural groups that were partitioned by colonial -- and later state -- boundaries. In such culturally fragmented states, social capital and inter-personal trust are concentrated within ethnic groups, resulting in lower levels of society-wide generalized trust. Scholars have often implied that territorial nationalism could ameliorate the problems resulting from cultural diversity, such low levels of trust, but the state-defined national identity in African states is typically argued to be too weak. To empirically evaluate the impact of national identity on trust an ethnically diverse region of Africa, I analyze original data collected from members of two partitioned ethnic groups living alongside the Malawian-Zambian border, including survey measures of strength of national identification, an experimental manipulation of the salience of a common national identity, and a behavioral economic measure of interpersonal trust. In contrast to the commonly held view, I find that conationality is a strong and robust predictor of interpersonal trust, and equal in magnitude to the effect of coethnicity. Further, preliminary results suggest that interpersonal variation in the strength of national identification is positively related to the degree to which trust is conditioned on shared nationality, and there is suggestive evidence that this may be especially true when the national identity is made contextually salient.