Gravity models of migration have become the standard tool to analyze the determinants of bilateral migration flows. The empirical evidence produced by the estimation of this model helps us to understand why the geographical distribution of migrants across destinations varies greatly for different migrant-sending countries. This, in turn, contributes to shape the development implications of international migration flows. Furthermore, gravity models have been used to predict the evolution of migration flows over the coming decades, and to establish a causal relationship between migration and development, following a standard practice in the trade literature.