This dissertation presents the results of a series of common pool experiments conducted in three regions of rural Colombia with individuals who face a social dilemma in their everyday lives that is similar to what was presented in the experiment. The research objectives are to develop an empirical characterization of how individual behavior deviates from purely self-interested Nash behavior and to further our understanding of the effects of alternative institutions to promote more conservative choices in common pool experiments. Groups of five subjects participated in a 20-period common pool resource game framed as a harvest decision from a fishery. Every group first played 10 rounds of a baseline limited access common pool resource game and then 10 additional rounds under one of five institutions: face-to-face communication, one of two external regulations, and communication combined with one of the two regulations. The two external regulations consisted of an individual harvest quota that was set at the efficient outcome, but differ with respect to the level of enforcement. A total of 420 individuals participated in the experiments, with individual earnings averaging slightly more than a day’s wages. The results are presented in three essays. The first essay, What Motivates Common Pool Resource Users?, develops and tests several models of pure Nash strategies of individuals who extract from a common pool resource when they are motivated by combinations of self-interest, altruism, reciprocity, inequity aversion or conformity. The results suggest that a model which balances self-interest with a strong preference for conformity best describes average strategies. The data are inconsistent with a model of pure self-interest, as well as models that combine self-interest with individual preferences for altruism, reciprocity and inequity aversion. The second essay, Communication and Regulation to Conserve Common Pool Resources, tests for interaction effects between formal
