New in paperback. Hardcover was published in 2020. This Handbook explores the activities of the UN development system (UNDS), the largest operational pillar of the organization and arguably the arena in which its ideational endeavors have made the biggest contribution to thinking and standards. Contributions focus on the role of the UNDS in sustainable social, economic and environmental development, describing how the UNDS interacts with the other major functions of the UN system, and how it performs operationally in the context of the SDGs.