The paper intends to present a case study report on how the ideas of Education for Sustainable Development were mainstreamed and integrated into national standards and curricula of basic and complete secondary education in Mongolia. First, we tried to give a proper definition of the terms such as ‘Sustainable Development’, ‘Education for Sustainable Development’ from Mongolian nomadic perspectives. The term ‘Sustainable Development’ in Mongolian context is, on the one hand, the integration of nature and quality of a matter (content and form), and on the other hand, it is the integration of ‘arga’ and ‘bilig’ (intelligence and practice). To live in one world, it is absolutely essential to stabilize the socio-ecological inequality for dealing with the urgent ecological crisis (Jadamba and Tungalag, 2015). Secondly, based on the Mongolian context, the studydefined the most important elements covering the three pillars of sustainable development that were to be used as the main indicators for the assessment of ESD mainstreaming into standards and curricula of basic and complete secondary education in Mongolia. With the help of clearly defined elements, we revisedthe education policy documents, the existing standards and curricula for basic and secondary education in Mongolia; carried out an assessment of ESD mainstreaming into standards, and curricula of basic and complete secondary education of Mongolia; prepared recommendations on how to improve the mainstreaming of ESD in standards and curricula.