The Global Agricultural Concept Scheme (GACS) is a SKOS concept scheme with concepts and related terms used in the field of agriculture, broadly defined. GACS is developed by the Food and Agriculture Organization of the United Nations (FAO), the Centre for Agriculture and Biosciences International (CABI), and the USDA National Agricultural Library (NAL), GACS was formed at the intersection of most-frequently-used concepts from their three respective thesauri -- the AGROVOC Concept Scheme, CAB Thesaurus, and the NAL Thesaurus, for which GACS provides a mapping hub. GACS is seen as an important step towards linking and integrating agricultural data of all types to address the long-term challenge of global food security.