I employed ethnographic field work, multi-village surveys, and a behavioral experiment to examine the influences of ethnic forces on cooperation in environmental management in the upper Palani Hills of Tamil Nadu, India. This dissertation is composed of three distinct studies.

In the first study, I present behavioral evidence from a public goods experiment that hierarchical caste combinations suffered reduced cooperation in comparison to non-hierarchical multi-caste groups. In comparison to highly cooperative play in single-caste groups, when 'high' and 'low' caste individuals played together, both reduced cooperation markedly, and the addition of a third, 'middle' caste, improved the both high and low caste cooperation.

A second study employs survey data to showing that while caste diversity may decrease volunteer irrigation labor and reduce irrigation fairness, the distribution of irrigation channels is itself biased, with greater irrigation connectivity for individuals in the more powerful castes. The irrigation access variable proves to be the most important predictor in regression analyses, pointing to a technologically embedded form of caste-based hierarchy.

The third study explores aspects of daily life hypothesized to be important in determining ethnic interactions. Mirroring my earlier results, I find that (1) ethnic stratification is more detrimental to cooperation than mere 'unranked' ethnic diversity, (2) social exclusivity is strongly increased by ethnic stratification, but that (3) directly reciprocal relationships are robust to cooperative failure across hierarchical ethnic boundaries where indirect reciprocity is not. These results extend our understanding of the anti-cooperative effects of ethnic differences in the area of natural resource management by coupling field experiments with ethnography and survey research. I supply fresh evidence that hierarchical ethnic divisions are more detrimental to real-world cooperation in general and in environmental management in particular than are non-hierarchical ethnic boundaries. In addition, I find evidence that direct reciprocal relationships may have an important role to play as a tool for enhancing cross ethnic cooperation.