Pinili is a 3rd class municipality with a total population of 17,300 as of the FY 2015 census of population. It was created under Executive Order No. 92 on January 1, 1920 through the initiative of Gabriel Pagdilao, Ignacio Lafradez, Buenaventura Lacuesta, Leoncio Pagdilao and Ruperto Valbuena.
It is composed of twenty-five (25) barangays. The two (2) poblacion/urban barangays are Valbuena and Pagdilao. The twenty-three (23) rural barangays are Upon, Nagtrigoan, Dalayap, Puritac, Badio, Capangdanan, Gulpeng, Apatut-Lubong, Darat, Bulbulala, Puzol, Tartarabang, Aglipay, Salanap, Barbar, Pugaoan, Bungro. Sto. Tomas, Cabaroan, Buanga, Liliputen, Lumbaan-Bicbica and Sacritan.