We use experimental data to obtain a detailed description of individuals' pro-sociality. Participants are faced with a large number of decisions involving variations in the tradeoffs between own and others' payoffs, as well as in other potentially important factors like individuals' positions...

Many experimental studies indicate that people are motivated by reciprocity. Rabin (1993) develops techniques for incorporating such concerns into game theory and economics. His model, however, does not fare well when applied to situations with an interesting dynamic structure (like many...