Barangay Nagbayan

Situated in Castillejos, Zambales, Barangay Nagbayan is one of 14 barangays that make up the municipality within Central Luzon.

According to the 2020 Philippine census, Barangay Nagbayan had a population of 3,602. This made it the 9th largest of 14 barangays in Castillejos by population, placing it in the middle tier of the municipality. Residents of Barangay Nagbayan accounted for approximately 5.31% of the total population of Castillejos, which stood at 67,889 in the same census year.

The barangay recorded 2,978 residents in the 2015 intercensal count and 3,602 residents in the 2020 Census — a net change of +21.0%, consistent with a growing settlement. Barangay Nagbayan is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Castillejos is a municipality comprising 14 barangays, and serves as the governing unit directly responsible for local services in Barangay Nagbayan, including public health, sanitation, peace and order, and civil registration. Within the wider province of Zambales, which contains 247 barangays across its component cities and municipalities, Barangay Nagbayan ranks 52nd by 2020 population. Zambales 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.