Social Capital and the Wages of Mexican Migrants / 671 * We would like to thank Dr. Lisa Catanzarite and Dr. Katharine Donato for their helpful comments and suggestions. We would also like to thank Dr. Nolan Malone for technical assistance with the MMP and Dr. Mary Fisher for her assistance with Figure 1. Please direct all correspondence to Michael B. Aguilera, Department of Sociology, P.O. Box 1892, Rice University, Houston, TX 77251-1892. © The University of North Carolina Press Social Forces, December 2003, 82(2):671-701 Social Capital and the Wages of Mexican Migrants: New Hypotheses and Tests* MICHAEL B. AGUILERA, Rice University DOUGLAS S. MASSEY, University of Pennsylvania Abstract In this article, we develop hypotheses about the ways in which network ties influence wages and the circumstances under which social capital assumes greater or lesser importance in the determination of migrant earnings. We then test these hypotheses using data on male Mexican migrants gathered by the Mexican Migration Project. We find that social capital has both direct and indirect effects on migrant wages. Indirectly, social capital influences how a job is obtained and whether it is in the formal sector. Directly, having friends and relatives with migratory experience improves the efficiency and effectiveness of the job search to yield higher wages. Moreover, the effects of social capital on wages are greater for undocumented than documented migrants, reflecting the more tenuous labor market position of the former. These results confirm and extend social capital theory and underscore the importance of social networks in understanding the determination of migrant earnings. The concept of social capital was introduced into social science by the economist Glenn Loury (1977) but was elaborated theoretically by the sociologists Pierre Bourdieu (1986) and James Coleman (1988). Since its incorporation into the field in the 1980s, it has been applied to a variety of social settings, from neighborhoods (Sampson and Morenoff 1997) to nations (Putnam 2000). Massey and colleagues (1987:170-71) were the first to apply the concept to migration, noting that poor Mexican peasants “may be poor in financial resources, but they are wealthy in social capital, which they can readily convert into jobs and earnings in the United States.”