When will ordinary people pour into the streets, risking life and limb to lay claim to their rights? The question has fascinated observers and frightened elites since the French and industrial revolutions. Outraged by the excesses of the mob and the dislocations of industrialization, early scholars saw contentious politics as the expression of the mentality of the crowd, of anomie and deprivation. But even a cursory look at modern history shows that outbreaks of contention cannot be derived from the deprivation people suffer or the disorganization of their societies. For these preconditions are far more enduring than the movements they support. What does vary widely from time to time and place to place are the levels and types of opportunities people experience, the constraints on their freedom of action, and the threats they perceive to their interests and values.

In this chapter, I argue that contention is more closely related to opportunities for – and limited by constraints upon – collective action than by the persistent social or economic factors that people experience. Contention increases when people gain the external resources to escape their compliance and find opportunities in which to use them. It also increases when they are threatened with costs they cannot bear or which outrage their sense of justice. When institutional access opens, rifts appear within elites, allies become available, and state capacity for repression declines, challengers find opportunities to advance their claims. When combined with high levels of perceived costs for inaction, opportunities produce episodes of contentious politics.