As “green public procurement” (GPP) is playing an increasingly important role in stimulating the demand for environmentally friendly products and services, there is a strongly emerging need to analyze which factors drive the inclusion of environmental criteria in public tenders. Working on data from Italian municipalities, our statistical analysis confirmed that intensifying information and raising awareness on GPP techniques can strongly support the development of public green tenders. Moreover, our work reveals that good GPP performance cannot be achieved through the mere adoption of a certified Environmental Management System (EMS) by a public authority alone, but rather through the level of maturity of the certified EMS that provides a growing “value added” to GPP practices. Finally, findings of this study demonstrate that the relevant limitations linked to the small size of public authorities can be overcome by the progress in GPP brought by several European, national and local supporting initiatives.