This report explores the ways donors can best support sustainable and effective climate-related capacity development in Small Island Developing States (SIDS), in terms (1) access to climate finance; (2) climate data and services; (3) working with non-governmental partners; (4) regional and triangular approaches; and (5) effective delivery of capacity development. Based on OECD data, it provides an overview of bilateral official development assistance trends for climate-related capacity development in SIDS during 2015-21. Drawing from donor project and programme evaluations, interviews, two case studies and a literature review, the report identifies good practices and makes recommendations to donors.