How does gender influence trust, the likelihood of being trusted and the level of trustworthiness? We compare choices by men and women in the Investment Game and use questionnaire data to try to understand the motivations for the behavioral differences. We find that men trust more than women, and women are more trustworthy than men. The relationship between expected return and trusting behavior is stronger among men than women, suggesting that men view the interaction more strategically than women. Women felt more obligated both to trust and reciprocate, but the impact of obligation on behavior varies.