This book emphasizes the importance of involving stakeholders in data formation related to assessments of hydropower development. This is a prerequiste if projects are to be sustainable. The study targets policy formation after the UNCED and UNSSD conventions, and how a discrepancy emerges between policy and its implementation by using hydropower development as an extended case. At global and national levels new policies make it mandatory for implementing agencies to introduce or expand social considerations far beyond old practices. This calls for new emphases in problem areas as well as methods to optimize the access information required by policy for proper implementation. By drawing on about a dozen project cases, with among others Swedish Sida support, examples show how policy change has gradually influenced project design and implementation, but also how this change process is slow and reliant on approvement from the dominating technical and economic traditions for project assessment. The reader will find a detailed account giving insight into the reality behind policy changes as they have evolved during the last decade and gradually permeated current policy, as expressed in the call for new data formation methods. The book provides a unique account for sustainable development related policy enforcement. It shows how the sustainability drive combines with democracy and grassroot involvement to influence the stakeholder formation of project details.