The effect of a partner's gender on the decision to be cooperative or noncooperative was assessed using a contemporary, real-world variant of the Prisoner's Dilemma game. Forty male and forty female college students were asked to imagine that they were gong on an oil expedition in which they could operatively choose to search together or uncooperatively choose to search alone. Each decision was made independently, but the outcome depended on both participants' decisions. It was found that although women cooperated more than men, men and women cooperated significantly more when their partner was a woman. Furthermore, in response to a question about partner cooperativeness, women rated their partners as more cooperative during the game whereas men rated their partners as more competitive. However, all of the participants made more noncooperative decisions as the game went on.