In contrast to the situation in the end of the XX century, today it is commonly accepted that public procurement (and public procurement law) has multiple points of contract with the objective of environmental protection and plays a critical role in integrating environmental concerns into the everyday activities and outputs of the public sector. This chapter offers a roadmap of the current principles, tools and debates of green or sustainable public procurement (SPP or GPP), from the point of view of European Union law, combined with some elements of national laws of European systems. We explore what can be called the “basic toolbox” of SPP, that is, the essential instruments by which environmental concerns are specifically acknowledged in public procurement law, and also some rising topics related to the protection of the environment during contract performance. Finally, specific attention is given to the very debated question of whether the law should evolve into a more incisive approach of mandatory SPP, namely looking at the reasons backing this approach, some examples of its implementation and a few challenges it raises.