This paper examines the impact of interethnic exposure on national integration in a multiethnic state. It uses variation arising from a mandatory program in Nigeria that randomly posted university graduates to different states of the country for a year of national service. I administer a survey to a cohort of university alumni seven years after their participation and compare participants who served in a state where they are the ethnic majority to those exposed to a state where they are not the majority. The results indicate two concurrent effects. First, interethnic exposure creates a stronger connection to the country: exposed participants have greater national pride, are more knowledgeable about other ethnic regions and are more willing to move to other ethnic regions. In line with this, I observe that they are four times as likely to be living outside their ethnic region. Second, consistent with social identity theory, immersion in a different culture also reinforces participants' connection to their ethnic group by highlighting distinctions between groups: they have greater ethnic pride and are more likely to have all their closest friends from their ethnic group. In addition, I find no evidence of increased closeness or trust towards other ethnic groups.