This article contributes to the research exploring the social and economic factors shaping the performance of immigrant-run firms. Drawing upon human and social capital theory and assimilation theory, we investigate differences in performance measured as revenue growth in a comparative study of native and immigrant CEOs. Following 50,002 small firms in Sweden over 4 years, we find distinct patterns in both firm size and revenue growth between firms managed by immigrants and by natives. While firms run by second-generation immigrants from the Organization for Economic Co-operation and Development (OECD) countries exhibit higher growth rates than natives, the reverse is true for second-generation immigrants from non-OECD countries, suggesting that economic integration in terms of small business growth immigrants in Sweden is characterized by segmented rather than universal assimilation.