Green Public Procurement (GPP) is an increasingly debated “demand side” environmental policy instrument . The aim of this paper is to take stock of the related literature, with the twofold aim of developing a conceptual model of the relevant phases of GPP and to identify the related research gaps in detail. The literature analyzed here comprises English language papers, which are focused on GPP during the time period from 2000 to 2016. By means of a systematic literature review and content analysis, we provide both a quantitative and qualitative viewpoint. As our analysis reveals, GPP discussion has mostly focused so far on the specific impacts of GPP implementation, while the discussion on GPP as compared to other environmental policy tools, in terms of efficiency and innovation, is still lagging behind; this is coupled with a limited geographical coverage. Finally, by disaggregating the 17 years period under scrutiny into four sub-periods allows us to outline the changes in research trends over time.