This book is based on a research in Watershed Management. Today, Watershed degradation , due to soil erosion, is considered a major challenge in the world.In Iran, despite the introduction of several projects aimed at mitigating this environmental menace,we are still facing with this problem. Issues related to technical and social complexities of the watershed projects are pretty difficult to evaluate, in spite of the lessons learnt from the past experiences. In order to address such challenges, it is essential to assess fundamental social and technical evaluations. The social evaluation study is designed to determine the factors that affect variation of level of participation in Watershed Management Program (WMP) in Iran. In this regard, a conceptual model is developed to identify characteristics that lead to the participation in WMP, and determine the factors that affect variation of level of participation. This book provides the first comprehensive presentation of social evaluation of watershed management programmes in the world.