Three basic purposes motivate this book. First, I seek to refine theories of social movement outcomes. I begin with the simple proposition that, to explain movement success or failure, more attention must be devoted to explaining the behavior of movement targets and bystanders (third parties). The core argument is simple: the target of any social movement, interest organization, or other benefit-seeker must discern the threat posed to its interests and the cost of capitulating to demands, and then respond accordingly. A mugger's declaration, “Your money or your life,” succinctly depicts a similar cost calculation. The transaction is coercive, but it is a transaction nevertheless. Factored into these considerations is the actual or anticipated behavior of third parties. Will anyone come to the victim's assistance? As E. E. Schattschneider (1960) famously declared, the audience to a struggle often determines the outcome. There is much truth to this axiom; however, most studies do not account for why some bystanders watch from the sidelines while others get involved, nor why they choose the side that they do. In the case of the mugging, a bystander to this crime must likewise weigh the relative importance of aiding the victim against the personal risk of intervening. Third parties, then, perform a similar computation to direct targets in which they consider how much the mugging affects them as well as the dangers of interceding.