In this dissertation I investigate the impact of market expansion upon peasant livelihood strategies and the on-farm conservation of crop genetic resources in the Guatemalan highlands. In particular, I explore how the formation and reconfiguration of different types of market activities in the Mesoamerican “megacenter” of agricultural biodiversity have shaped the relevance and practice of cultivating milpa - a peasant agricultural practice where maize is intercropped with beans, squash, medicinal herbs and other useful plants for direct household consumption. I focus upon the diversity of the three principal milpa crops - maize, legumes, and squash - during the current era of globalization (1980 - 2005).

On the macroeconomic level, I find that the neo-liberal restructuring of the Guatemalan economy that began in the 1980s has undermined the country's long history of maize self-sufficiency and contributed to the loss of crop genetic resources, ultimately threatening local and global food security. Economic liberalization is associated with a substantial reduction in the share of agricultural land allocated to maize - including many genetic hotspots - and an influx of imported grain. Additionally, neo-liberal agricultural policies have pushed farmers in many centers of maize genetic diversity to abandon the crop in favor of non-traditional agricultural exports.

Drawing upon quantitative and qualitative fieldwork in two highland communities, I also investigate the processes that shape peasant livelihood strategies and the cultivation of milpa diversity at the household level. Four variables are consistently linked to the level of diversity maintained on the farm: (1) agricultural biodiversity is positively associated with the size of farmers' arable landholdings; (2) peasant households maintain diversity as a means for hedging against the risks of environmental uncertainty and the caprices of market-based income sources; (3) cultivating diversity is a form of recreation and a means for expressing cultural identity; and (4) reliance upon hired field hands is negatively associated with diversity management.

In contrast to the predictions of many economic theorists, I find that most forms of market participation are complementary to the cultivation of crop genetic resources. The complementarity is attributable to the structure of Guatemala's rural economy and several non-market entailments generated by milpa agriculture.