Economic exchange often pits options for selfish and cooperative benefit against one another. Decisions favoring communal profit at the expense of self-interest have traditionally been thought to stem from strategic control aimed at tamping down emotional responses centered on immediate resource acquisition. In the present article, evidence is provided to argue against this limited view of the role played by emotion in shaping prosociality. Findings demonstrate that the social emotion gratitude functions to engender cooperative economic exchange even at the expense of greater individual financial gains. Using real-time inductions, increased gratitude is shown to directly mediate increased monetary giving within the context of an economic game, even where such giving increases communal profit at the expense of individual gains. Moreover, increased giving occurred regardless of whether the beneficiary was a known individual or complete stranger, thereby removing the possibility that it stemmed from simple awareness of reciprocity constraints.