The Nazi Party/Foreign Organization was a branch of the Nazi Party and the 43rd and only non-territorial Gau ("region") of the Party. In German, the organization is referred to as NSDAP/AO, "AO" being the abbreviation of the German compound word Auslands-Organisation ("Foreign Organization"). Although Auslands-Organisation would be correctly written as one word, the Nazis chose an obsolete spelling with a hyphen.

Nazi Party members who lived outside the German Reich were pooled in this special Party department. On May 1, 1931 the "AO" was founded on the initiative of Reich Organization Leader (German: Reichsorganisationsleiter) Gregor Strasser, and its management was assigned to Hans Nieland, who resigned from office on May 8, 1933, because he had become head of the Hamburg police authority; he was replaced by Ernst Wilhelm Bohle. Only actual citizens of the German Reich with a German passport could become members of the AO. Persons of German descent, ethnic Germans (German: Volksdeutsche), who possessed the nationality of the country in which they lived, were refused entry to the Nazi Party.