Does kindness pay for everyone? We suggest that acting kindly promotes social capital gains, but only for the poor. In Study 1, we found that among 737 Americans, donating in the past month was positively related to having more Facebook friends, but only among people with low income. In Study 2, in an online getting-to-know-you chat paradigm, 560 people tended to enjoy interacting with partners they perceived as prosocial than non-prosocial, but only if they believed the partner to have low income. In Study 3, we expanded these findings to the global level, demonstrating a higher percentage of the population donating is positively related to number of friendships on Facebook, but only for low GDP per capita nations.