Modelling tourism development cycles associated with planning and investment cycles intends to be a contribution to the understanding of the tourism activity within a continuum process. It allows a better apprehension of the sequence of interdependencies that exist and can be addressed enlarging the well-known concept of tourism product and its life-cycle. The model sketched in this paper is still under progress and has been adapted from the territorial plan-process model (Lourenço, 2003) which is based on the quasi-model of Holton
