In the age of migration, many developed countries face an increasing heterogeneity of their residents. Migrant flows often lead to political discussion about the impact of migrants on labour markets, economic growth, and urban agglomeration processes, and consequently many of these causalities are a source for debate in policy circles and academic research. In this paper on migrant impact analysis we offer a broad, though not exhaustive, overview of research on migration effects and economic development. The impact of migrants on economic growth and development depends strongly on the scope and scale of research, such as the geography of the labour market and the heterogeneity of migrants. In general, no clear negative impact of migration on the economy is found on an aggregate level and in the long run. In the short run, however, some adjustment processes are clearly at work on the regional level. But, more research and data gathering is necessary to point out the exact relationship between migration and economic growth. Migrant diversity, labour markets, economic growth, agglomeration externalities