This article attempts to fill the void in research on the Justicialista Party (PJ) organisation. Challenging accounts of the contemporary PJ as a weak, personalistic organisation, it argues that the party maintains a powerful base-level infrastructure with deep roots in working- and lower-class society. This organisation has been understated by scholars because, unlike prototypical working class party structures, it is informal and highly decentralised. The PJ organisation consists of a range of informal networks – based on unions, clubs, NGOs and activists' homes that are largely unconnected to the party bureaucracy. These organisations provided the government of Carlos Menem with a range of benefits in the 1990s, particularly in the realm of local problem-solving and patronage distribution. Yet they also constrained the Menem leadership, limiting its capacity to impose candidates and strategies on lower-level party branches.