This paper reviews common challenges faced by researchers interested  in measuring the impact of migration and remittances on income, poverty,  inequality, and human capital (or, in general, "welfare") as well as difficulties  confronting development practitioners in converting this research into policy  advice. On the analytical side, the paper discusses the proper formulation  of a research question, the choice of the analytical tools, as well as the interpretation of the results in the presence of pervasive endogeneity in all  decisions surrounding migration. Particular attention is given to the use of  instrumental variables in migration research.