Barangay Rosario

Situated in Diadi, Nueva Vizcaya, Barangay Rosario is one of 19 barangays that make up the municipality within Cagayan Valley.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Rosario had a population of 324. This made it the 18th largest of 19 barangays in Diadi by population, placing it among the smaller barangays of the municipality. Residents of Barangay Rosario accounted for approximately 1.68% of the total population of Diadi, which stood at 19,236 in the same census year.

The barangay recorded 313 residents in the 2015 intercensal count and 324 residents in the 2020 Census — a net change of +3.5%, consistent with a growing settlement. The Philippine Statistics Authority classifies Barangay Rosario as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Diadi is a municipality comprising 19 barangays, and serves as the governing unit directly responsible for local services in Barangay Rosario, including public health, sanitation, peace and order, and civil registration. Within the wider province of Nueva Vizcaya, which contains 275 barangays across its component cities and municipalities, Barangay Rosario ranks 266th by 2020 population. Nueva Vizcaya is classified as a 2nd by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Like every Philippine barangay, Barangay Rosario is led by an elected Punong Barangay (barangay captain) supported by seven Sangguniang Barangay members (kagawads), an SK Chairperson, a Barangay Secretary, and a Barangay Treasurer. The next Barangay and Sangguniang Kabataan Elections (BSKE) are scheduled for Monday, November 2, 2026, with officials serving four-year terms under Republic Act No. 12232.