The project will strengthen knowledge and capacity for sustainable urban and peri-urban forestry management and policy in the UNECE region. Activities will also seek to foster the enhanced implementation of sustainable urban forestry that recognizes its contribution to sustainable development, climate action, and resilient cities. This builds on work and results achieved as part of the “Trees in Cities Challenge” (TICC) under two previous projects (Supporting UNECE member States in building capacity on urban forestry, E353, February - December 2020, and Supporting UNECE member States to integrate the maintenance, protection, and restoration of urban and peri-urban trees and forests in their post COVID-19 recovery plans, E373, February - December 2021). Two-thirds of humanity will live in cities by 2050. Achieving national sustainable development objectives and the SDGs depends on healthy and resilient cities and their surroundings. Responsible for around 75% of global CO2 emissions, cities in the UNECE region and beyond are key to fighting climate change and are also highly vulnerable to its impacts. Trees and forests in urban and peri-urban areas are simple and cost-effective nature-based solutions to these challenges. They provide vital tree and forest ecosystem services for health, biodiversity, and climate adaptation and mitigation. Unlocking the full potential of urban and peri-urban trees and forests as powerful nature-based solutions depends on the quality and sustainability of urban forestry. This requires appropriate policies and careful long-term planning that bridges traditional silos between stakeholders from various sectors, and the local and national level, and moving from a focus on planting to growing trees in cities, recognizing them as green assets that increase in value over time. The project aims to spur city-level capacity and knowledge that enables and fosters action to implement sustainable urban and peri-urban forestry as a nature-based solution and delivery mechanism for sustainable, climate-smart development in the UNECE region. It will foster sustainable urban forestry based on interdisiplinary approaches, planning  and actions, such as urban agroforestry, gardening or food forests for combating urban food deserts and insecurity, engaging the community and private owners, and linking city action with national objectives and international agendas.