Collective action theory, which is widely applied to explain human phenomena in which public goods are at stake, traditionally rests on at least two main tenets: that individuals confront discrete decisions about free riding and that formal organization is central to locating and contacting potential participants in collective action, motivating them, and coordinating their actions. Recent uses of technologies of information and communication for collective action appear in some instances to violate these two tenets. In order to explain these, we reconceptualize collective action as a phenomenon of boundary crossing between private and public domains. We show how a reconceptualized theory of collective action can better account for certain contemporary phenomena, and we situate traditional collective action theory as a special case of our expanded theory.