Close to 300 million people today reside in countries in which they were not born, and migrants have been growing as a share of the world’s population for decades now. I study the various mechanisms through which these migrant communities (diasporas) impact their home countries. In my talk I will focus on two studies, one for Albania and one for Colombia. The first study measures the impact of return migration from Greece to Albania on Albania’s economy, in the aftermath of the 2009 Greek sovereign debt crisis. The second one studies the characteristics that make a diaspora more likely to engage back home, and more likely to return. It introduces the largest diaspora survey known to us. Throughout the talk, I will elaborate on the aspects that make a diaspora well-positioned to contribute to the development of their home country, and the mechanisms through which a diaspora makes development happen.