Societal-level social capital ultimately rests upon individual attitudes and behaviors. This study investigated the determinants of individuals' preferences for real versus ersatz social activities. Ersatz social activities are substitutes for true social interaction; they involve interaction with media or media characters rather than other individuals. Undergraduates (N = 144) chose activities from pairs of social and ersatz exemplars. The participants were randomly assigned to one of four conditions. In two of these conditions, they wrote essays designed to create either a positive or negative mood; in the other two conditions, they read essays designed to highlight either the costs or benefits of friendship. Results indicated that individuals low in trust were susceptible to situational influences. Low-trust individuals chose more real social activities when in a positive mood or when benefits of friendship were salient, whereas they chose ersatz social activities when in a bad mood or when costs of friendship were salient. High-trust individuals showed relatively high preference for real social interactions regardless of mood or the salience of costs and benefits. These results suggest that appropriate interventions should overcome low trust to build social capital.