Transboundary water treaties are established to prevent disputes over shared rivers between states. Nevertheless, empirical studies indicate that international organizations manage to bring cooperation between states in some cases and fail in others. This research explains why the efforts of international organizations to promote water cooperation sometimes succeed or sometimes fail and which factors contribute to their varying levels of success in different cases? International organizations are more likely to achieve cooperation between states with strong characters (less change in power dynamics) and share mutual benefits than weaker states (frequent shift in power dynamics) and have less shared benefits. I will examine how shared benefits and the character of the state can help international originations achieve cooperation or conflict that can be influenced by power asymmetry or by creating an imbalance/balance of power (causal mechanisms). Thus, weak riparian countries are less likely to achieve cooperation, increasing the probability of conflict. The hypothesis is tested on the Nile River Basin and the Indus River Basin, using a comparative analysis. The findings indicate an important relationship between the state’s characters, shared benefits, and the role of international organizations in bringing cooperation and preventing conflict between riparian states.