Apart from the city of Siena the principal towns are Poggibonsi, Colle di Val d'Elsa, Montepulciano, Chiusi, and San Gimignano.

From 1945 to 1995 the President of the province of Siena was chosen by the members of the Provincial Council, elected every five years by citizens.

From 1995 to 2014, under provisions of the 1993 local administration reform, the President of the Province was chosen by popular election, originally every four, then every five years.

President (Commissioner) and members of Council are elected together by mayors and city councilors of each municipality of the province respectively every four and two years.

[2] In each province, there is also a Prefect (prefetto), a representative of the central government who heads an agency called prefettura-ufficio territoriale del governo.