Planting trees in the agricultural landscape, in the form of establishing agroforestry systems, has a significant role to play in potentially improving ecosystem services, such as increased biodiversity, reduced soil erosion, increased soil carbon storage, improved food security and nutrition, and reduced greenhouse gas emissions. While the role of trees in agroforestry systems in improving ecosystem services has been researched, studies in new systems/regions and new agroforestry system designs are still emerging. This Special Issue includes selected papers presented at the 4th World Congress on Agroforestry, Montpellier, France 20-22 May 2019, and other volunteer papers. The scope of articles includes all aspects of agroforestry systems.