This thesis examines the challenges to cooperation encountered by organised workers and poor communities trying to unite their forces in post-apartheid South Africa. I employ the case study approach to investigate the relationship between a local branch of the South African Municipal Workers Union (SAMWU) and social movements as participants in the Cape Town Anti-Privatisation Forum (APF). The analysis explicates the way APF activities have been challenged both by national political dynamics and by organisational aspects in the local. Issues that emerge range from the hegemonic position of the African National Congress in South African society, to the different organisational dynamics of the local APF organisations. I also examine how this specific cooperation between a trade union and community organisations can shed light on a general understanding of this kind of cooperation, as they are understood in theories of social movement unionism.