Across the world, we observe different experiences in terms of inequality between migrant and 'host-country' populations. What factors contribute to such variation? What policies and programmes facilitate 'better' economic integration? This paper, and the broader collection of studies that it frames, speaks to these questions through focused comparative consideration of two migrant populations (Vietnamese and Afghan) in four Western countries (Canada, Germany, the UK, and the US). It pays particular attention to involuntary migrants who fled conflict in their home regions beginning in the 1970s. The paper builds in particular on the literature on segmented assimilation theory, exploring new linkages with work on horizontal inequality, to highlight the role of five key sets of factors in such variation: governmental policies and institutions; labour market reception; existing co-ethnic communities; human capital and socioeconomic characteristics; and social cohesion or 'groupness'.