As of the census of 2000, there were 3,466 people, 779 households, and 701 families residing in the CDP. The population density was 2,003.6 people per square mile (773.5/km²). There were 817 housing units at an average density of 472.3/sq mi (182.3/km²). The racial makeup of the CDP was 28.85% White, 0.55% African American, 1.64% Native American, 3.58% Asian, 61.17% from other races, and 4.21% from two or more races. Hispanic or Latino of any race were 83.96% of the population.
There were 779 households out of which 60.7% had children under the age of 18 living with them, 71.4% were married couples living together, 11.6% had a female householder with no husband present, and 10.0% were non-families. 8.1% of all households were made up of individuals and 4.0% had someone living alone who was 65 years of age or older. The average household size was 4.44 and the average family size was 4.60.
In the CDP the population was spread out with 38.0% under the age of 18, 14.2% from 18 to 24, 27.6% from 25 to 44, 14.8% from 45 to 64, and 5.4% who were 65 years of age or older. The median age was 24 years. For every 100 females there were 118.3 males. For every 100 females age 18 and over, there were 117.0 males.
The median income for a household in the CDP was $25,313, and the median income for a family was $24,750. Males had a median income of $20,469 versus $17,188 for females. The per capita income for the CDP was $7,034. About 34.7% of families and 39.6% of the population were below the poverty line, including 48.6% of those under age 18 and 20.0% of those age 65 or over.
In the state legislature Terra Bella is located in the 16th Senate District, represented by Democrat Dean Florez, and in the 30th Assembly District, represented by Democrat Nicole Parra. Federally, Terra Bella is located in California's 21st congressional district, which has a Cook PVI of R +13 and is represented by Republican Devin Nunes.