Many development analysts assert the importance of democratic social organizations, but few either document, or analyse the actual processes of internal democracy. This study examines part of the broader problem of the 'Iron Law of Oligarchy' - the ebbs and flows of leadership accountability over time. Drawing on the history of a Mexican regional peasant organization since 1974, the analysis suggests that different kinds of organizational structures encourage or discourage membership action, but moments of mass direct action in turn shape the ways in which organizational structures actually distribute power. The case analysis shows how the interaction of internal and external factors shaped the balance of power between leaders and members at each critical turning point. Participatory subgroups turn out to be the crucial counterweight to concentrated leadership power, mediating relations with the membership and providing alternative sources of leadership. Whether formal or informal, multiple vertical channels and alternative horizontal linkages between membership groups are crucial complements, and sometimes substitutes, to conventional organizational structures.
