This handbook takes voluntary associations as the starting point for making sense of communities. Although the way associations and the organization of local social life are intertwined is one of the oldest approaches to community study the way citizens and residents come together informally to act and solve problems has rarely been a primary focus. There is little direct research or theory dealing with this subject and beginning to correct that deficit is the task of this book. The challenge accepted by this book is important because associations are central to important, developing areas of social theory and social action. For example, the theory of civil society is based on the notion that informal groups, social movements, civic associations, and small formal nonprofit organizations form a cohesive set of social organizations that integrate society. Grassroots and community-based organizations exist between the private social world of the family and the formal, professional contractual world of large organizations. They include PTAs, block associations, fraternal organizations and self-help groups (like Alcoholics Anonymous) as well as congregations, Internet chat clubs, and political action movements. They provide venues and opportunities for personal expression. At the same time they build social capital, become vehicles by which communities define and solve their problems, and link residents with the larger political realm. Considering their importance, we are surprised that there is neither research nor theory telling us where they come from, how they work, and how they interface with important aspects of local social life. There also is growing interest in nonprofit or nongovernmental organizations as vehicles for social advocacy, policy making, and the implementation of social programs. Most research and analysis has dealt with large, paid staff nonprofits. Yet research has demonstrated that more than 90% of theorganizations and resources in the nonprofit sector exist among smaller, more voluntary organizations. There is virtually no research on this dark matter of the nonprofit universeon what it is; how it functions; and how it makes its impact felt. This book builds a theory of local organizations. We have asked leading researchers drawn from diverse areas of research and social theory whose work overlaps with the world of local associations offer theoretical perspectives and review relevant literature. For most of the authors this meant thinking about a familiar area of research from a new and original point of view. The result is a synthesis that gives a new perspective on voluntary organizations and for the first time an integrated yet diverse theoretical understanding of this important aspect of community life. Each author was asked to teach his or her specialty area to a generalist audience. The chapters are accessible and authoritative without being burdened with technical jargon. The goal is a book that will form the foundation stone for a discipline in social science study and a sophisticated resource that will be useful to practitioners around the world.