Third parties have been active in assisting adversarial states to navigate their international river disputes. By using the carrot and stick to facilitate compromise, mediators have also participated in the negotiations leading to the signing of treaties over international rivers. Yet, due to the nature of the issue confronting riparian states, the long-term impact of these efforts is likely to be unstable cooperation rather than cooperation. This is still an important contribution, because the absence of mediation efforts may contribute to an environment of conflict. However, since riparian states confront a relationship that involves the need to continuously manage disputes that arise as states develop their international rivers, a mediator may be more effective in facilitating cooperation if it assists developing states with a history of animosity to establish effectively designed river basin commissions and it oversees the implementation of treaties. Participating in the initial years of a treaty's implementation by coordinating the donor community to underwrite projects can minimize the potential disputes riparians confront. An effectively designed river basin commission can assist in facilitating cooperation long after the mediator has departed from the region. To demonstrate this argument, the article draws on the Indus River case, which has lived through four different phases. The Euphrates and Tigris Rivers are used to illustrate the argument's ability to explain other cases.