Thailand’s Fourth National Communication (NC4) has been prepared in accordance with UNFCCC guideline. The NC4 is a medium for Thailand to communicate its commitment to fulfilling the obligations under Article 4.1 and 12.1 of the UNFCCC. It presents updated and more comprehensive information on the national circumstances; institutional arrangements; national greenhouse gas (GHG) inventory; mitigation policies, plans, and measures; achievement of GHG emissions reduction under NAMA; preparation for the implementation of NDC; vulnerability and adaptation; other information and activities relevant to climate actions; and constraints, gaps, support needed, and support received to implement its adaptation and mitigation actions. The chapter on vulnerability and adaptation also serves as Thailand’s first adaptation communication.