The workshop was convened by the United Nations Environment Programme (UNEP) Global Programme of Action (GPA), Global Partnership on Marine Litter (GPML), and the Coordinating Body on the Seas of East Asia (COBSEA). Organized in the context of the COBSEA Regional Action Plan on Marine Litter (RAP MALI) and the COBSEA-UNEP SEA circular initiative, the workshop aimed to present and promote a national source inventory approach in national marine litter planning and monitoring. This document provides a summary of issues discussed, identifies relevant resources, and includes a list of participants. All presentations are available online at www.cobsea.org. For more information on national source inventories and capacity development opportunities through COBSEA, the GPML and GPA, kindly contact unep-cobsea@un.org.