Purpose: Examined here are some of the tenets of social capital in the context of the migrants' crossing the U.S.-Mexico border without official authorization. Using this context helps identify how social capital development is weakened by the structural and gendered dimensions of migration, contributing to the rise in undocumented border crosser deaths since 1993. Approach: A selection of published works provide an overview of social capital, and in particular, how the framework has been used to further our understanding of the process of migration and immigrant settlement in new destinations. The principles of social capital are then examined in light of women's border crossing experiences and used to argue that migrants from emerging migrant-sending states in southern and central Mexico have had less time to accumulate resource-enhancing migrationrelated social capital. The narratives of repatriated women collected during research on the border in 2006-2007 are used to illustrate how controlling environments undermine the acquisition of social capital at a critical time. Findings: The selection of narratives of women who were repatriated after attempting to cross into the United States without authorization illustrate the perilous interplay of hardening border enforcement and multiplying illicit border smuggling organizations. The outcome is the downward leveling of social capital on the border that potentially poses greater life-threatening risks for migrants. Originality/value: This study provides a theoretical understanding that can be used to explain rising levels of violence along the U.S.-Mexico border that increasingly engulf migrants fleeing poverty in Mexico.