This paper reviews the impact of international migration on socio-economic development in sending regions. Migration and remittances have considerably improved living conditions, income, education and spurred economic activity through agricultural, real estate and business investment, from which non-migrants indirectly profit. This has transformed migrant-sending regions such as the Rif, Sous and southern oases into relatively prosperous areas that now attract internal ‘reverse’ migrants. Although this challenges prevailing pessimism, the developmental potential of migration is not fully realized due to several structural constraints. Migration impacts are heterogeneous across space, socio-ethnic and gender groups, and tend to change over time and household migration cycles. Depending on the specific development and investment context, migration and remittances may enable people to retreat from, as much as to invest in, local economic activities,. Paradoxically, development in migrant-sending regions seems to be a prerequisite for return and investment rather than a consequence of migration.