Any trust situation involves a certain amount of risk for trustors that trustees could abuse. In some cases, intermediaries exist whoplay a crucial role in the exchange by providing reputational information. To examine under what conditions intermediary opinioncould have a positive impact on cooperation, we designed two experiments based on a modified version of the investment gamewhere intermediaries rated the behaviour of trustees under various incentive schemes and different role structures. We found thatintermediaries can increase trust if there is room for indirect reciprocity between the involved parties. We also found that the effectof monetary incentives and social norms cannot be clearly separable in these situations. If properly designed, monetary incentivesfor intermediaries can have a positive effect. On the one hand, when intermediary rewards are aligned with the trustor’s interest,investments and returns tend to increase. On the other hand, fixed monetary incentives perform less than any other incentiveschemes and endogenous social norms in ensuring trust and fairness. These findings should make us reconsider the mantra ofincentivization of social and public conventional policy.