Barangay San Isidro

Barangay San Isidro is a mid-sized barangay in the municipality of Castilla, located in the province of Sorsogon, in the Bicol Region region of the Philippines.

According to the 2020 Philippine census, Barangay San Isidro had a population of 4,292. This made it the 2nd largest of 34 barangays in Castilla by population, placing it among the most populous barangays of the municipality. Residents of Barangay San Isidro accounted for approximately 7.08% of the total population of Castilla, which stood at 60,635 in the same census year.

The barangay recorded 4,139 residents in the 2015 intercensal count and 4,292 residents in the 2020 Census — a net change of +3.7%, consistent with a growing settlement. Barangay San Isidro is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Castilla is a municipality comprising 34 barangays, and serves as the governing unit directly responsible for local services in Barangay San Isidro, including public health, sanitation, peace and order, and civil registration. Within the wider province of Sorsogon, which contains 541 barangays across its component cities and municipalities, Barangay San Isidro ranks 18th by 2020 population. Sorsogon is classified as a 2nd by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

The barangay's legislative and executive affairs are handled by a Punong Barangay and the Sangguniang Barangay, elected nationwide during the Barangay and SK Elections. The next BSKE is scheduled for Monday, November 2, 2026, following the synchronized election schedule set by COMELEC Resolution No. 11191.