We examine collaboration patterns of foreign scientists working in one of 16 countries in 2011 and compare them to the collaboration patterns of nonmigrant scientists and scientists with some international experience who have returned. Data come from the GlobSci survey. Major findings are that both foreign-born scientists and returnees have larger international research networks than do native researchers who lack an international background. The higher incidence of international collaboration among migrants is driven primarily by those who did not get their PhD training in the destination country but rather came for a postdoctoral position or directly for employment. We also find that a sizeable share of foreign born collaborate with researchers located in their country of origin and that migrants are also likely to collaborate with individuals from their home country who are working or studying in a third country (diaspora effect). Finally, the relative strength of the origin country's science base matters in the sense that those who come from a relatively stronger base have superior networks compared to those coming from a relatively weaker science base.
