STANAG is the NATO abbreviation for Standardization Agreement, which set up processes, procedures, terms and conditions for common military or technical procedures between the member countries of the alliance. Each NATO state ratifies a STANAG and implements it within their own military. The purpose is to provide common operational and administrative procedures and logistics, so one member nation's military may use the stores and support of another member's military.

STANAGs are published in English and French, the two official languages of NATO, by the NATO Standardization Agency in Brussels.

Among the standardization agreements are those for calibers of small arms ammunition, map markings, communications procedures, and classification of bridges.