Public participation (PP) is increasingly expected to enhance the effectiveness of water resources management. This is recognized in recent legislation such as the European Union Water Framework Directive. We identify five key constituents that affect the success of PP processes and which can be used as indicators thereof. These comprise: 1) the scope of the participants; 2) communication with the public; 3) capacity building; 4) timing; and 5) financing of participation. They are based on the management of resources—namely time, human and financial resources—and on further aspects that emerge from the utilization of these resources throughout the PP process. Drawing on existing case studies from the European Union and Canada, we demonstrate the applicability of our evaluative scheme. We find severe deficits in the PP cases that can all be attributed to the five key constituents. Although not representative, our analysis points to important challenges for water policy, particularly in the European multi-level context.