Rational choice analysis of collective action predicts that individual members of a large group will not contribute voluntarily towards a common cause; members of large groups attribute no significance to individual action. Large groups are mobilised by the attraction of private goods and services; private interest, rather than identity with a common cause, is the stimulus. Yet the efficacy of such selective incentives depends on the signal that erstwhile 'profits' (from the provision of private goods) are dedicated to achieving a collective goal. At the same time, the signal that collective action is 'non-profit' enhances the intrinsic value of the act of participation. When the impact of individual action on outcome is difficult to discern, individuals rely on low-cost signals relating to process. There are incentives to identify with the pursuit of a common cause when collective action is deemed 'non-profit' and a common goal is non-rival.