Temporary organizations have been known and studied for many years, but there are still many unknowns. Since the founding writings on the subject in the 1970s, the scientific community has continued to develop knowledge and to highlight the specific characteristics of this type of structure. However, as has recently been highlighted, the transition from the state of a potential project to that of a project in progress remains particularly poorly understood. Often referred to as transitional phases, these periods of change are still poorly defined. After presenting the literature on transitional phases, the paper aims to highlight that these phases are primarily dedicated to the transfer of coordination from the strategic top to the logistic functions. The main academic contribution of the paper lies in the proposal of a conceptualisation of transitional phases around three main dimensions: the construction and mobilisation of an organisational memory, the introduction and stabilisation of managerial innovations, and the evolution of the mode of coordination of actions. From an empirical point of view, the paper is based on multiple case studies from the field of event management in the broadest sense, including sports and musical events, as well as popular festivals