Abstract: The standard model of binary moral hazard with limited commitment is extended by allowing the principal to offer mechanisms with mediated communication. A simple necessary and sufficient condition is exhibited under which mediated communication allows to partly restore the efficiency loss due to the lack of commitment and to enhance effort provision with respect to the non-mediated benchmark. Furthermore, two examples of applied interest are provided where non-mediated mechanisms fail to attain the upper bound of the principal’s payoff and to implement a Pareto-efficient allocation, whereas mediated mechanism succeed in both respects.