Countries in the Arab region host a large share of the global migrant worker population. Estimating the exact size of this population is an arduous task, given the increasing complexity of migration flows and the high prevalence of refugees and workers with an irregular immigration status. According to latest available ILO statistics, the Arab States – comprising the Middle East and countries of the Cooperation Council for the Arab States of the Gulf (GCC) – hosted 24.1 million migrant workers in 2019, constituting the subregion with the highest proportion of migrants in its labour force (41.4 per cent) compared with 4.9 per cent globally. Migrant workers are especially visible in the GCC countries, where they make up the vast majority of workers in the private sector. North African countries have a lower share of migrant workers; the region accounts for 74.3 million workers, of which 1.6 per cent are migrant workers. This brief aims to examine barriers to the social security of migrant workers in the Arab region, identify current practices and chart possible avenues for progressive reforms. It first reflects on the importance of extending social protection to migrant workers from the vantage point of international labour and social security standards. Second, the brief presents a typology of drivers of exclusion that prevent access to social security across the Arab region. It then delves into the instruments available to migrant workers in the Arab region against different contingencies, with a focus on current best practices. Finally, the report concludes with a number of proposals for a progressive reform agenda, which would advance the universal right to social protection for migrant workers in the region.