LAUSR

Research on collective action problems and the provision of public goods has yielded an array of important insights into why people sacrifice for their groups, but ignores the processes that bring people into those groups in the first place. The literature is also silent on the fact that groups providing similar public goods often compete with one another to attract new members. We extend the reach of theories of collective action problems to bring them to bear on these interrelated issues. Results from four experiments support our predictions about when group members compete to attract new adherents by sacrificing more for group goals. Further, we find that prospective members join more productive groups at much higher rates and then contribute to them at high levels. These processes give way to cumulative advantage, whereby initially productive groups continually attract new members. Thus competition for members can yield large inequalities in the size and success of collective action groups.