One of the main challenges of today?s analyticalgeography is the back-linking of observed phenomena toindividual actions, as not determined by individuals?structural situation in a one-goal society but by theirvery choice of spatial goals, i.e. by what shall becalled individuals? actor-dimension. In this paper wepresent an actor-based model of urban residentialmobility. Results show that public policies in urbandevelopment must take into account and act on thisactor-dimension if they are not to obtain effectsopposite to their aims.