We present a new and simple mechanism for repeated public good environments. In the Conditional Contribution Mechanism (CCM), agents send two message of the form, "I am willing to contribute x units to the public good if in total y units are contributed." This mechanism offers agents risk-free...

We investigate whether and how social ties affect performance in teams by implementing a field experiment in which a sample of undergraduate students are randomly assigned to either teams composed by friends or teams composed by individuals not linked by friendship relationships. Students...

We designed a natural-field experiment in the context of local public transportation to test whether rewards in the form of lottery prizes coupled with traditional sanctions efficiently reduce free-riding. We organized a lottery in a medium-size Italian city the participation in which is linked...

Recent international climate negotiations suggest that complete agreements are unlikely to materialize. Instead, partial cooperation between like-minded countries appears a more likely outcome. In this paper we analyze the effects of such partial cooperation between like-minded countries. In...