In this article we analyze patterns of emigration and return to Mexican communities located in traditional migratory regions and in new emigration communities. The traditional communities of origin are located in the states to the far west of Mexico and the new origin communities are located to the south of Mexico City or in states near the Mexico.S. border. We estimate discrete time event history models predicting the likelihood of departure and return on first trips to the United States, and departure and return on subsequent trips. In both sets of communities we find that social capital is crit cal in raising the odds of departure on a first trip, but declines in importance in predicting the odds of departure on later trips, which are influenced more This content downloaded from 157.55.39.58 on Tue, 11 Oct 2016 04:55:45 UTC All use subject to http://about.jstor.org/terms .LAS S. MASSEY, JORGE DURAND Y FERNANDO RIOSMENA primer viaje, pero declina su importancia para predecir las probabilidades de partida de los viajes siguientes, que estan mas influenciados por el capital humano relativo a la migracion. Los migrantes de ambos grupos de comunidades usan la migracion internacional como medio para financiar la adquisicion de viviendas y de negocios, pero los migrantes de nuevas comunidades emisoras buscan primero negocio y luego las propiedades inmobiliarias, mientras que entre los de comunidades tradicionales es a la inversa. Los esfuerzos por parte de los Estados Unidos de impedir las migraciones entre Mexico y Estados Unidos militarizando la frontera han fallado, especialmente entre los migrantes de comunidades emisoras tradicionales que tienen tradiciones migratorias muy establecidas y acceso al capital humano y social especifico a la migracion. by migration-related human capital. Migrants from both sets of communities use international migration as a means of financing the acquisition of homes and businesses, but migrants from the new origin communities seek businesses first and then homes while among those from traditional communities it is the reverse. The efforts made by the United States to prevent Mexico-U.S. migration by militarizing the border have failed, especially among migrants from traditional sending communities with wellestablished migratory traditions and great access to migration-specific human and social capital.