This dissertation focuses on the evaluation of the obstacles on the way towards a militant and democratic, grassroots trade unionism. Therefore, it is an ethnography of trade union organising. At a general level this study deals with the relationship between labour and capital in the Irish mushroom industry in the context of global capitalism and the Irish national institutional framework. This is reflected at a theoretical level in the opposition between the political economies of labour and capital. At a more concrete level, this dissertation centres on workers' resistance to exploitation and the struggle of capital to overcome it. While the first part of the thesis deals with that struggle on mushroom farms, the second part tells about the efforts of organised labour in Ireland to 'clean up' the worst aspects of exploitation in the mushroom industry. In the second part of the dissertation, a second contradiction arises, that between the interests and dynamics of labour institutions, such as trade unions and workers‘ based Non-Governmental Organisations, and workers‘ collective interests. This second contradiction, which I consider a reflection of the main contradiction between capital and labour, motivates the title of this dissertation, 'Workers against Institutions'. This does not imply that I make a case against organised labour; it merely means that workers have also to fight against the influence of the hegemonic political economy of capital within their own organisations, which is reflected in tendencies such as 'reformism', 'partnership trade unionism', and bureaucratic tendencies as opposed to rank-and-file unionism, and 'popular power'.