The literature on Entrepreneurial Ecosystems has increasingly raised a conceptual interest of studying Entrepreneurial Support Organizations (ESOs), recognizing the importance of their role in spurring ecosystem development. However, the specific outcomes these various types of organizations provide for the territories involved remain underexplored. The ESO element has often been treated as a monolithic block, yet it encompasses diverse entities that may have different influences and impacts on the entrepreneurial environment. This thesis work seeks to address this gap in the Entrepreneurial Ecosystem literature by first creating an updated and comprehensive mapping of incubation and acceleration activities, focusing the analysis on Italy, the Netherlands, and Ireland.