ABSTRACT This article surveys interactions between migration and inequality, concentrating mainly on the impact on income inequality of rural to urban migration. To study the impact of migration requires a prior understanding of the processes determining income distribution, so the main theories of the latter are briefly surveyed, including subsistence, neoclassical, institutional, and structural models. In each case the main theme is labour market functioning. The impact of migration in each of these models is then discussed, partly in terms of the properties of the models themselves, partly in terms of plausible migration scenarios. The empirical literature is briefly surveyed, covering characteristics of migrants; integration of migrants in destination areas; urban-rural interactions in terms of remittances, terms of trade, and return-migration; and macro-economic issues. It is concluded that the impact of migration on inequality differs greatly according to the mode of production and the model used to describe it. On the basis of the evidence reviewed, the more common outcome seems to be for migration to reduce inequality overerall (mainly by reducing differentials between origin and destination areas), but migration can also help to perpetuate inegalitarian production systems. Finally it is commented that migration is endogenous to most production systems to that its effects cannot be adequately analysed without also examining its causes.