This work is a joint publication of the Organisation for Economic Co-operation and Development (OECD) and the United Nations Development Programme (UNDP). It is Part II (of III) of a report that presents the results of the 2018 Monitoring Round of the Global Partnership for Effective Development Co-operation. Part II focuses on how effectively development partners support partner country-led efforts for sustainable development. Data collected by 86 partner countries and territories, in collaboration with more than 100 development partners, serve as the basis of this work and its evidence regarding implementation of the agreed principles of effective development co-operation: country ownership, focus on results, inclusive partnerships, and transparency and mutual accountability. By highlighting where progress has been made and where challenges remain, the work aims to inform how governments and their partners can strengthen collective action towards achievement of the 2030 Agenda for Sustainable Development.