Barangay Diliman I

Classified as a mid-sized barangay, Barangay Diliman I is one of the administrative divisions of San Rafael in Bulacan, Central Luzon, Philippines.

According to the 2020 Philippine census, Barangay Diliman I had a population of 3,634. This made it the 12th largest of 34 barangays in San Rafael by population, placing it in the middle tier of the municipality. Residents of Barangay Diliman I accounted for approximately 3.52% of the total population of San Rafael, which stood at 103,097 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay Diliman I changed from 3,340 to 3,634, a shift of +8.8% over the five-year period. This places the barangay among those with growing populations in San Rafael. Barangay Diliman I is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

San Rafael is a municipality comprising 34 barangays, and serves as the governing unit directly responsible for local services in Barangay Diliman I, including public health, sanitation, peace and order, and civil registration. Within the wider province of Bulacan, which contains 569 barangays across its component cities and municipalities, Barangay Diliman I ranks 328th by 2020 population. Bulacan is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Barangay Diliman I is governed by an elected Sangguniang Barangay composed of a Punong Barangay and seven kagawads, with the Sangguniang Kabataan representing the youth. The next BSKE, set for Monday, November 2, 2026, will elect officials to four-year terms as provided under Republic Act No. 12232.