The purpose of this chapter is to introduce the concept of ‘green corridors’ as a means to develop integrated, efficient and environmentally friendly transportation of freight between major hubs and by relative long distances. The basis of this material is work conducted in the context of the EU SuperGreen project, which aimed at advancing the green corridor concept through a benchmarking exercise involving Key Performance Indicators (KPIs). The chapter discusses the available definitions of green corridors and identifies the characteristics that distinguish a green corridor from any other efficient surface transportation corridor. After providing examples of green corridor projects in Europe, it focuses on the KPIs that have been proposed by various projects for monitoring the performance of a freight corridor. Emphasis is given to the SuperGreen KPIs, covering the economic, technical, environmental, social and spatial planning aspects of freight logistics, as they have been scrutinized extensively by stakeholders in order to keep their number within practical and operable limits. In addition, the chapter presents the performance monitoring methodology that was developed by SuperGreen in an effort to close the gap of earlier works. The lessons learned from SuperGreen lead to a revised methodology suitable for monitoring the performance of a corridor.