The paper investigates contemporary political and ideological shifts of Cuban socialism paying specific attention to the period of actualization of Cuban socio-economic model of development implemented since the VI Congress of the Communist party of Cuba. The analysis is based on the different variants of Cuban Constitutions and proposes three historical models of Cuban socialism (Marxist-Leninist, the model of transition and the actualization period model). Comparing the texts of the Constitutions, the study sheds light on several key aspects: the role and functions of the State and the Party, ideological problems of socialism, communism and Marxism, the evolution of the exploitation and oppression concepts, issues of equity and equality, and appeal to the figure of J. Marti. Using historical method, comparative analysis and Marxist theory, as the latter has been the base for the first model of Cuban socialism under investigation, the paper reveals the role of Marxism within the three models. The study uncovers the contradiction between postulating a significant role of Marxism within the actualization model and revision of several core Marxist principles as well as the turn towards national issues in the contemporary Cuban socialism.