The article seeks to present an outline of the relationship between socialists, communists and radical leftists in the Greek party system from 1974 to 2020. The article emphasizes the ideological convergence or divergence surrounding the content of a left-wing strategy and, the political coalitions that arose during this period. It identifies three critical junctures (1974, 1992, 2010) which conditioned the development of the relationship between socialists, communists and radical leftists in Greece, which correspond to three related periods of study (1974-92, 1992-2010, and 2010-2020). Finally, it analyzes the four factors that precluded the convergence of socialists, communist and radical leftists: historical legacies of the labour movement in Greece; government-opposition dynamics; conservative party strategies; and intra-party cohesion and conflict.