The author examines the difficulties but also the possibilities of taking lived-in spaces into account when elaborating territorial projects within the context of public participation in the project. Individual spatialities, established according to an original method of investigation and re-evaluating the notion of lived-in space through that of said spaces, have neither a scale nor a structure which can correspond to institutional spaces of public action. The individual’s dwelling is defined as the method and content of justifications for evocations of spaces and places that are frequented or simply thought of. Different types of justification are specified: qualification, explanation, rationalization. This dwelling allows us to distinguish between, in an archetypal manner, individuals who refer first and foremost to one or more spatial models constructed during their lives, and those who, in contrast, refer to one or more spatial models of a relational kind (two examples are examined). The first category can be taken into account by planners, the second with much greater difficulty.