Twelve of the thirteen historical communities of Santorini merged into a single municipality by Law 2539/1997 (plan "Kapodistrias"). By the same law the Community Oia combined with the brotherly community of the island of Thirassia.
With this shape our islands was ruled from 1999 until 2010, whereafter, by Law 3852/2010, the so-called "Kallikrates Plan", Thira Municipality included the Community Thirassia-Oia in a single administrative arrangement, covering the whole cluster of islands of Santorini. Administered by the Mayor and the Municipal Council elected every 5 years by universal voting.
As every municipality is divided into compartments called "municipal units" and these in turn into "communities". The latter have their own boards, however their role is advisory and can not take decisions.
Our municipality is composed of the Municipal Units Thira and Oia, subdivided in turn in Municipal Communities corresponding to the historical communities of islands: Thirassia, Oia, Vourvoulos, Imerovigli, Fira, Karterados, Messaria, Vothonas, Episkopi Gonias (Kamari - Exo Gonia), Exo Gonia, Pirgos, Megalochori, Emborio, Akrotiri.
Thira Municipality is an organic part of the South Aegean Region based in Ermoupolis of Syros and further Decentralized Administration of the Aegean, based in Piraeus.
Along with Ios, Sikinos, Folegandros and Anafi municipalities establish the Thira Regional Unit.
According to the census of 2012, people residing in our Municipality amounts to 15550.