Since the early 1980s the Communist Party of Spain (PCE, Partido Comunista de España) began a process of party change that prominently included strategies thought to affect the role of party members and the linkage of the party with its social milieu. The party developed from the mid 1980s a plan to give form a new organization, United Left (IU, Izquierda Unida), in the creation, impulse and design of which the PCE would have an absolutely key role. In this organizational strategy, the Communists included the explicit purpose to give IU a more democratic internal functioning, granting the rank and file would have more influence in decision-making processes than in traditional parties. The PCE’s design of IU also included the goal of having closer and wider relations with old and new social movements, opening the traditional left towards a more intense relationship with a broad catalogue of social organizations. Throughout the last 25 years the PCE and IU have experienced rise and defeat and, simultaneously these strategies have also experienced impulse and decadence. This paper describes and gives an account of their design and implementation and evaluates the specific outputs produced in the two fronts, namely the participatory (membership) and the policy-responsiveness (interest groups) linkages.