The Croatian Republic of Herzeg-Bosnia (Croatian: Hrvatska Republika Herceg-Bosna) was an entity in Bosnia and Herzegovina that existed between 1991 and 1994 during the Bosnian War. It was proclaimed on 18 November 1991 under the name Croatian Community of Herzeg-Bosnia, and claimed to be a separate or distinct "political, cultural, economic and territorial whole" in the territory of Bosnia and Herzegovina. Herzeg-Bosnia never proclaimed secession from Bosnia and Herzegovina nor declared such a goal in any official statement, officially recognizing sovereignty of Bosnia and Herzegovina. In spite of that, the International Criminal Tribunal for the former Yugoslavia (ICTY) concluded that Herzeg-Bosnia was founded with the intention to secede from Bosnia and Herzegovina and unite with Croatia. According to ICTY, these aspirations, supported by the Republic of Croatia, were manifest, among other things, by Herzeg-Bosnia's use of Croatian currency and Croatian language and the granting by the Republic of Croatia of Croatian citizenship to the Croats of Bosnia and Herzegovina. The Constitutional Court of the Republic of Bosnia and Herzegovina declared the Croatian Community of Herzeg-Bosnia illegal on 14 September 1992. Herzeg-Bosnia ceased to exist in 1994 when it was joined to the Federation of Bosnia and Herzegovina upon the signing of the Washington Agreement by the authorities of Croatia and Bosnia and Herzegovina.
The official capital city of Herzeg-Bosnia was western Mostar. However, since Mostar was a war zone, the effective control centre was in Grude.