In complex fields, change requires cooperation from numerous dispersed actors with divergent interests. Guided by reference works and articles, we draw on complementary insights from institutional and plural leadership in team theories to enrich the emerging notion of Collective Institutional Entrepreneurship. In this sense, this work focuses on the micro mechanisms by which actors engage collectively in entrepreneurial actions and highlights the structural and organized character involving the action of many individuals acting under the same entity: the "Collective". Our research is based on a case study called the "Espace Partagé de Santé Publique", which has been established in 2005 to favor social innovations targeting disabled individuals. Collective Institutional Entrepreneurship takes many forms varying from the institutional work in witch actors are involved. It shows how collective institutional entrepreneurship relies on shared competencies and on the sharing of multiple resources derived from a diversity of actors working in a collaborative effort. This case study shows how experiments such as EPSP are conducive to the emergence of Collective Institutional Entrepreneurship involved in the design and implementation of a social innovation. The platform provides a large set of various resources, and institutional entrepreneurs can use its to establish a social innovation project. Regarding the structure and dynamics of Collective Institutional Entrepreneurship, the main results of this study invite future investigations to consider the richness of collective dynamics to apprehend complex institutional changes.