This dissertation focuses on two problems in Brazilian left politics: fragmentation and depoliticization. There is consensus inside the Brazilian left regarding its fragmentation, but the scenario requires a careful analysis of fragmentation since the conjunctural change of June 2013. The same can be said about depoliticization, explained here through the phenomena of post-politics and ultra-politics, and which is arguably the marker of the difficulties the left has found to mobilize the working class even as this class is under attack. This dissertation fills the gap in the literature by addressing these two problems from the Gramscian-influenced perspective of a crisis of praxis. The concept of a crisis of praxis is proposed to attend to the misalignment between theory and practice at the leftist organizational level that has led to melancholia and distance from the consciousness of the class, despite the potential held by new mobilizations – both spontaneous and organized. It is argued that without properly addressing fragmentation and depoliticization, the left will have trouble appealing to the working class, especially given the conclusions of a crisis of representation that was exposed in Brazil in June 2013 and capitalized on by right-wing conservative forces in order to foster political instability in their favour.