These case studies complement the 2018 Development Co-operation Report: Joining forces to leave no one behind. Case study contributors share knowledge and lessons on what it takes to answer the pledge of the 2030 Agenda for Sustainable Development to leave no one behind through national and sub-national policies, strategies and programmes as well as international development co-operation projects, programmes and partnerships. The insights, good practices and lessons shared in these case studies were provided by diverse actors. These include official development co-operation ministries and agencies from members of the OECD and the Development Assistance Committee, international organisations, developing country governments, civil society organisations, business, and research bodies. The case studies highlight experiences from projects and programmes in leaving no one behind and reaching the furthest behind. They are organised and presented under two broad categories: 1. Reaching and including people and places; 2. The enabling role of international co-operation: policies, partnerships and data.