The article presents the main tenets of the UNESCO Programme on Man and Biosphere (MAB), launched by the United Nations at the beginning of the 1970s. The program aimed at supporting applied research and scientific knowledge for managing natural resources in a rational and sustainable way. The implication of the full ecological perspective, typical of the MAB, for promoting multidisciplinary and integrated approaches in the study of environmental issues is briefly outlined. In particular, we point out the role of the MAB, through the biosphere reserve concept, in supporting the collaboration between natural-biological and social-behavioral sciences when dealing with biodiversity conservation problems and with urban ecosystems. Then, the specific UNESCO-MAB Project on the city of Rome, launched at the end of the 1980s, is briefly presented, together with the recent project of the Department of the Environment of the Rome Municipality to propose Rome's urban and periurban green areas as a new UNESCO-MAB Biosphere Reserve. The results of the main research activities conducted therein are summarized. In particular, the specific research lines of the environmental psychology research group, involved in the MAB-Rome Project for approximately two decades, are presented. These research lines dealt with various aspects of residents' environmental perceptions and behaviors in the city of Rome. The practical implications of these results are also briefly discussed.