The Minangkabau of West Sumatra have long been noted for both a high level of outmigration and a tradition of an eventual return home, but some writers believe that migration from west Sumatra has become more permanent in recent years. Survey data collected in 1970-71 point to 4 main types of mobility in West Sumatra: commuting, local trading, circular migration and medium and long-term migration, with the last type being by far the most important is most of the villages surveyed. An analysis of Census and survey data suggests that perhaps half of all medium and long-term migrants from West Sumatra are now permanent migrants, and there is some evidence that this proportion is increasing with successive generations. The consequent decline in the degree of circularity in Minangkabau mobility is likely to result in a reduction in the flow of resources from migrants back to their home villages, leaving fewer positive benefits to counteract th negative effects of out migration.