The logistics industry causes various harms to the environment. The literature assigns the main responsibility for alleviating such harms to two supply chain actors: shippers (logistics buyers) and logistics service providers (LSPs), which motivated studying them in this thesis. Specifically, this thesis explores and identifies how green logistics practices can be facilitated through aligning both actors throughout the different phases of their relationships. Two studies are compiled. The first study is based on five distinct cases -- three shippers and five LSPs, providing the basis for two papers: (i) one that analyses the institutional pressures (regulatory, market, competitive) on shippers to purchase green logistics services, and on LSPs to provide these services, and (ii) one that investigates the two actors’ stances on environmental concerns in the four key logistics purchasing phases (request for proposal, negotiations, contracting, execution), while proposing ways to align their efforts along such phases. The second study covers a single case of a dyadic relationship between a shipper and its LSP, handling enhancing logistics performance (cost efficiency, on-time delivery) in the early stages of their relationship. The findings indicate a general lack of regulatory pressure in driving shippers and LSPs to engage in green logistics, contrasted by a long-term influence of competitive pressure and a prevalent influence of market pressure. It was also found that both actors must put substantial efforts in the beginning of their relationships to reach a mutual business understanding, allowing performance and green enhancements. In the execution, it was found that both partners should regularly communicate performance metrics while modifying working standards, which would also support their green practices. For practitioners, insights are offered to align shippers’ and LSPs’ efforts within their relationships to attain positive performance and green outcomes. / <p>QC 20180223</p>