What determines one's ethnic identity? I argue that contact with a co‐ethnic encourages an enhanced ethnic identity compared to contact with a non‐co‐ethnic. This is most likely to hold where identities are more ethnic and less national, as in many African countries, thus creating a sense of trust among co‐ethnics. To test this claim, I conducted a field experiment with participants from the West African countries of Côte d'Ivoire and Senegal using two designs to test my claims including if enumerators and participants share an ethnic identity established directly with face‐to‐face contact, and indirectly with enumerators employing ethnic sounding names. Social contact in which ethnicity is shared increases identification with one's ethnic group. Not sharing an ethnic identity does not increase the chances of a national identity. Variation by ethnic groups is strongest for members of groups who have recently lost political power or are marginalized. Sharing an ethnic identity affects political views. These findings contribute to our understanding about the potential for contact to affect prejudice and bias, and they raise issues about data collection done with personal contact.