“…First, key actors include government regulatory entities, procurement and environmental professionals, politicians, firms, the media, and civil society organizations [49]. Second, key drivers of GPP include personnel skills, green consciousness, clarity and specificity of policies, and environmentally friendly products/vendors information [45]. Third, the barriers to adoption of GPP can be grouped by institutional aspects (including culture, the lack of a relevant legal framework, lack of political will, lack of training and employee competences, stakeholder pressures, and the lack of long-term planning), issues related to the improvement of informational mechanisms (poor monitoring and inspection systems, inadequate policy measures, limited knowledge about the social and environmental impacts), the ability to make decisions in public managers (limited capacity of stakeholders, budget constraints, and lack of top management support), and market conditions and perceptions (unavailability of green products, the relative higher costs/prices of the sustainable options, the perception that sustainable items can restrict competition) [15,35,37,48,52,53].…”