This paper examines the role of cooperativeness and impatience in the exploitation of common pool resources (CPRs) by combining laboratory experiments with field data. We study fishermen whose main, and often only, source of income stems from the use of fishing grounds with open access. The exploitation of a CPR involves a negative interpersonal and inter-temporal externality because individuals who exploit the CPR reduce the current and the future yield both for others and for themselves. Economic theory – which assumes the existence of general across-situational traits – thus predicts that fishermen who exhibit more cooperative and less impatient behavior in the laboratory should be less likely to exploit the CPR, which our findings confirm. We thus corroborate the economic theory and extend the scope of other-regarding preference theories to crucial economic decisions with lasting consequences for the people involved. In addition, we establish cooperativeness and impatience as two distinct traits related to resource conservation in the field and validate laboratory preference measures.