This chapter discusses the inconsistent usage of ‘ethnicity’ in research on inequality in educational attainment, ranging from a generic term for any immigrants and minorities to racial categories through the identification of specific groups with a belief in a common heritage and culture in the Weberian sense. It reviews the two main approaches to explaining ethnic inequality in educational attainment research. The first, ‘structuralist’ approach attempts to reduce ethnic differences to resource differences in economic, social and human capital. Applying the general status attainment model to migrant minorities, parents invest resources into the education of their offspring. Findings from various studies demonstrate, however, that this ‘reductionist’ approach results in unexplained ‘ethnic residuals’. The second, ‘culturalist’ approach attempts to identify and explain additional differences between ethnic groups with regard to their ‘cultural tool boxes’, those carried over from their society of origin or developed in their minority situation in a receiving society. Although this approach works well in explaining the special case of successful East Asian migrant minorities, a comprehensive understanding of cultural effects on educational attainment remains underdeveloped in the literature.