The role of causal beliefs in people's decisions when faced with economic problems was investigated. Two experiments are reported that vary the causal structure in prisoner's dilemma-like economic situations. We measured willingness to cooperate or defect and collected justifications and think-aloud protocols to examine the strategies that people used to perform the tasks. We found: (i) Individuals who assumed a direct causal influence of their own action upon their competitor's action tended to be more cooperative in competitive situations. (ii) A variety of different strategies was used to perform these tasks. (iii) Strategies indicative of a direct causal influence led to more cooperation. (iv) Temporal cues were not enough for participants to infer a particular causal relation. It is concluded that people are sensitive to causal structure in these situations, a result consistent with a causal model theory of choice (Sloman & Hagmayer, 2006).