Since its foundation more than 50 years ago, regional science became an applied field. But applied regional science is still weakly epistemologically grounded. With the evolution of modern societies, taking more into account the people and their environment, questions are raised on its ideologies and basic concepts. As such regional science is not objective but a construct. This paper deals with the epistemological foundations of regional science, to show its scientific limitations and to propose a behavioral approach to be closer with the views of people, the ultimate objects of planning and investments decisions.