The aim of this paper is to illustrate how social innovation is promoted and spread by cooperative clusters in order to develop regional change. This paper focuses on the main drivers of the spreading and exaptation processes of social innovation. The cooperative cluster model, the exaptation concept, the top-down approach, the meso-institutions concept and the meso-level perspective are used to capture the strategic approach of spreading social innovation. The study analyses two successful clusters: Mondragon, made up of industrial SMEs, and Anecoop, an agricultural cooperative group, both leading clusters in their respective region. Qualitative methodology is used to compare both case studies. Among the findings, this paper is one of the first attempts to explain the territorial institutionalisation of social innovations by way of their exaptation. It presents adaptation and exaptation as distinct but partly sequential processes: the adaptation of social innovations in cooperative clusters paves the way for the subsequent leap via exaptation of these innovations in the whole of the territory