In a laboratory one-shot public good game, Fischbacher, Gachter and Fehr (2001) classify 50 percent of the subjects as conditional cooperators. Outside the lab, using a student sample, Frey and Meier (2005) find that people behave pro-socially, conditional on others' behavior. This paper tests...

In a natural experiment, this paper studies the impact of an informal sanctioning mechanism on individuals' voluntary contribution to a public good. Cross-country skiers' actual cash contributions in two ski resorts, one with and one without an informal sanctioning system, are used. I find the...