This paper illustrates the divergent party alliances established by former corporatist organisations to influence policymaking after the demise of oneparty rule in Mexico. Using a Most Similar Systems Design, the analysis suggests that variations in outcome owe to: a) the extent to which the organisation was relevant for advancing and implementing the agenda of the new presidential party and b) the ability of the organisation in question's leadership to loosen its formal ties with the PRI. The argument is grounded on threeThe authoritarian regime that held power in Mexico from 1929 to 2000 was underpinned by the subordination and dependence of sectoral organisations (including labour unions, the peasantry and popular associations) to the hegemonic party -the Institutional Revolutionary Party (Partido Revolucionario Institucional, PRI) and therefore the state. In this corporatist arrangement, 1 these organisations were kept in line through a series of legal provisions -including mandatory membership, representational monopoly, governmental recognition and restrictions on protest activities. In exchange, the leaders of official organisations were guaranteed political representation, policy influence and access to state subsidies and welfare services. In order to receive these benefits, the rank-and-file had to follow the orders of their leaders, who, in turn, were accountable to the president and the party in power.This corporatist structure thus allowed the PRI to control social dissidence, cement loyalties within the Mexican electorate and ultimately to remain in power for seven decades overall. However, beginning in the 1980s, the PRI began to lose more municipalities and governorships to opposition parties. It lost its majority in the lower house of C