<p>Privatisation, as a process that assigns more individual property rights, implies in most cases institutional change. Privatisation might occur on the level of society, when formal laws, but often also informal rules are changing, or it might take place on an organisational level when an asset under an open access regime, a cooperative, or a state-owned company is converted into a privately managed entity. From this perspective, it seems obvious that theories of institutional change provide a certain understanding of privatisation processes in the marine realm. Processes of marine privatisation are very heterogeneous in their characteristics: some processes are informal, some take part in the business world, others in the political realm, some are to a certain degree planned, others are emerging and have more evolutionary characteristics, some are characterised by huge power asymmetries others take place under more equal footing. Therefore, this paper interrogates a broad range of theories of institutional change. Our perspective does not proclaim or investigate superiority of one theory above the other, but rather inquires about <i>fit</i>. After elaborating on the theories, clarifying their focus, core concepts and assumptions, the paper illustrates the explanatory powers of the theories by looking at the case of privatisation of space in Saint Louis, Senegal. Due to strong restrictions for Senegalese fishers to fish in Mauritanian waters, the establishment of a marine protected area, and more recently the establishment of a gas field on the doorstep, fishers are confronted with an enclosure of their commons.</p>