Those tasked with the planning and construction of infrastructure and development operations face an increasingly uncertain context in which they must address risks across a number of different fields. These range from the environmental and archaeological to the social, political and financial. As a consequence, the formal and informal practices of stakeholders often incorporate projections of risk and opportunity. Project Risks analyzes this paradigm shift. It reviews the origin and nature of these uncertainties, and the practices implemented by the actors to mitigate or take advantage of them. Paradoxically, these practices generate new risks and power relations that are not compatible with the collaborative planning model. These paradoxes force the rethinking of practices such as project territorialization, risk taking in planning and the responsibility of actors, as well as the societal and political choices that must be made between the realization of projects and the protection of the environment.