This book has a central core for the formation of cooperative alliances among only the third sector organizations (OTS), nowadays, the literature has been showing works considering more the alliances from the third sector with the Government and Private Companies, which are known as intersectorial alliances. Another important reason is that there are very little academic literature about the subject. It analyzes the relevant factors to the construction of strategic alliances containing only OTS, called Social Alliances. This way, the book is recommended for professionals, such as: entrepreneurs, managers, teachers who work in strategic field, both in private enterprises and in the third sector organizations. Finally, the project was divided in 4 steps: motivating factors; selection criteria; governance structure and evolutive dynamics, in order to analyze how to build the social alliances.