Research into common pool resources from the field and in the laboratory has provided a series of insights for the successful management of such resources. The consequences of action and inaction in managing common pool resources are often most strongly felt (gains or losses) by local people. Several ecosystem services can be considered CPRs but in some cases the benefits of (mis)management are enjoyed by one group while the costs are levied on another group. Here we discuss some of the key findings of the CPR literature and how these relate to key considerations for using PES as a management tool. We focus on the role that ecosystems play in regulating water flows in two basins in Tanzania where feasibility studies have been conducted for the potential implementation of PES for water. We find that the lessons from CPR research shed light on some of the key implementation problems for PES mechanisms, and provide a useful guide for highlighting important user-resource considerations especially in contexts similar to East Africa, (C) 2010 Published by Elsevier B.V