International migration is attracting increased attention from governments, international agencies, non-government organizations, and scholars throughout the world (see, e.g., Castles and Miller, 1995; UN 2004, 2005, 2006, 2009; World Bank and Wodon, 2006). The United Nations has estimated that the global stock of international migrants (living in a country different from that of their birth) has more than doubled since 1975, reaching 213 million persons in 2010, or 3.1% of the world population. While this appears to be a modest increase compared to the figure of 2.9% in 1960, most of this increase has occurred in the past 15 years (UN, 2009), with migrants coming mainly from a few dozen developing countries and arriving in a much smaller number of high-income countries than had been the case before, often provoking xenophobic reactions. At the same time, remittance flows to developing countries have increased much more rapidly, reaching $338 billion globally in 2008 and dipping temporarily to $317 billion in 2009 during the global economic crisis (Ratha et al. 2009). On a global scale the total annual value of these remittances now greatly exceeds that of ODA (Overseas Development Assistance) from all multilateral and bilateral sources and rivals that of total annual private capital investment in developing countries. This has attracted the attention of governments and international agencies as it can be a major factor in lowering poverty, stimulating investment by households and economic growth, and, at the macro level, improving the balance of payments of recipient countries.