In the industrial cleaning sector, barriers to unionization are numerous and of all kinds. They are related to the structure of the internal labor market, conditions of employment and work, and the social profile of employees and so on. Do they totally hinder the development of trade unions and the conduct of industrial action? Or do the latter succeed in overcoming them through a renewed approach and an offer of something specific? These are the questions the text addresses in focusing on the policies and practices of trade unions operating in that sector, and examining their ability to cope with different forms of flexibility used by companies in that sector.