ADRION covers eight Partner States, of which four are EU Member States (Croatia, Greece, Italy and Slovenia), three are candidate countries (Albania, Montenegro, Serbia) and one is a potential candidate country (Bosnia and Herzegovina). The geographical area of each Partner State covers its national territory except for Italy, where programme area covers 12 regions and 2 provinces.

EU Partner States:

• Croatia: 2 regions (Jadranska Hrvatska, Kontinentalna Hrvatska)
• Greece: 13 regions (Anatoliki Makedonia – Thraki, Kentriki Makedonia, Dytiki Makedonia, Thessalia, Ipeiros, Ionia Nisia, Dytiki Ellada, Sterea Ellada, Peloponnisos, Attiki, Voreio Aigaio, Notio Aigaio, Kriti)
• Italy: 12 regions and 2 provinces (Abruzzo, Molise, Puglia, Basilicata, Calabria, Sicilia, Provincia Autonoma di Trento, Provincia Autonoma di Bolzano/Bozen, Veneto, Friuli-Venezia Giulia, Lombardia, Emilia-Romagna, Umbria and Marche)
• Slovenia: 2 regions (Vzhodna Slovenija, Zahodna Slovenija)

Non-EU Partner States

• Albania
• Bosnia and Herzegovina
• Montenegro
• Serbia