Diaspora networks provide information to future migrants and influence both their decision to migrate and their success in the host country. While the existing literature explains the effect of networks on migration decisions through the size of the migrant community, we show that the quality of the network is an equally important determinant. We argue that networks that are more integrated in the society of the host country can give more accurate information about job prospects to future migrants. In a decision model with imperfect signalling we show that migrants with access to a better network are more likely to make the right decision – they migrate only if they gain – and they migrate earlier. We test these predictions empirically using data on recent Mexican migrants to the US, and exploit the geographic diffusion of Mexicans since the 1980s as well as the settlement of immigrants that came during the Bracero program in the 1950s to instrument for the quality of networks. The results provide strong evidence that connections to a better-integrated network lead to better outcomes after migration. Yet we find no evidence that the quality of the network affects the timing of migration.