The emergence of the post-modern heralds the eclipse of the two dominant modes of socialist orthodoxy in the twentieth century - social democracy and Leninism. These developments are often taken as signalling the exhaustion of socialism in general. The demise of orthodoxy, however, encourages a reconsideration of long marginalised strands of socialist thought and practice, the left communist tradition. Socialist orthodoxy was a statist project, conquered by the goals of capital accumulation, nationalism and social security. Breaking from this mode of politics and vision of the good society, post-modernism today stands as an inescapable intellectual and political horizon for socialists. Of particular note are the post-modern rejections of scientific guarantees, vanguardist representation and the vision of social transparency. Similar rejections figure within the left communist tradition. However, some aspects of post-modernism work against socialist aspirations; notably the tendency towards uncritical pluralism, a retreat from any explicit theorisation of capital and the state, and an often fragile utopian dimension. Left communism addresses these shortcomings. Believing that freedom and community can be achieved only through a collective project, left communists are committed to a radical extension of popular sovereignty against domination by the state and capital. They adhere to cosmopolitan values and to the goals of classical social theory, while rejecting vanguardism in all its forms. Most importantly, seeking a life beyond proletarianisation, left communism retains a robust sense of utopian possibilities. On these grounds, this thesis argues that a negotiation between left communism and post-modern leftism promises a future for socialism in the contemporary period.