Abstract
In a series of experiments, we test the relative efficiency of persuasion and commitment schemes to increase and sustain contribution levels in a Voluntary Contribution Game. The design allows to compare a baseline consisting of a repeated public good game to, respectively, four manipulation treatments relying on: an information strategy, a low commitment strategy, a high commitment strategy and a promise strategy. We confirm the advantages of psychologically orientated policies as they increase the overall level of contribution and for some, that is commitment and promises, question the decreasing trend traditionally observed in long term contributions to public goods.