This article traces the origins and reasons for the 'Lineamientos de la Politica Economica y Social del Partido y la Revolucion' (Guidelines for Economic and Social Policy of the Party and the Revolution) adopted by the sixth Communist Party of Cuba Congress held in April 2011. It explains how this broad economic plan envisages a transformation of the Cuban economy utilising market mechanisms that are aimed at preserving socialism, in contrast to the former socialist countries where the reforms that were undertaken changed the system, rather than adapting it. The article uses economic data to discuss the progress made in the adoption of the principles contained in the Guidelines, analyses the problems that remain to be solved and offers some predictions as to the course of future developments. It concludes that the new reforms will allow Cuba to move gradually towards a sustainable socialist society without abandoning the principles of solidarity that characterise it, and which will compare favourably to the alternative that neoliberalism offers today.