MCBH is home for the 3rd Marine Regiment, as of 1994, under the U.S. 3rd Marine Division.
According to the United States Census Bureau, the base has a total area of 15.1 km² (5.8 mi²). 11.4 km² (4.4 mi²) of it is land and 3.7 km² (1.4 mi²) of it is water. The total area is 24.74% water.
As of the 2000 Census, there were 11,827 people, 2,332 households, and 2,283 families residing in the town. The population density was 1,040.2/km² (2,696.2/mi²). There were 2,388 housing units at an average density of 210.0/km² (544.4/mi²). The racial makeup of the base was 66.60% White, 12.07% African American, 1.09% Native American, 5.34% Asian, 1.19% Pacific Islander, 7.58% from other races, and 6.12% from two or more races. 14.64% of the population were Hispanic or Latino of any race.
There were 2,332 households out of which 66.7% have children under the age of 18 living with them, 93.0% were married couples living together, 3.7% have a female householder with no husband present, and 2.1% were non-families. 1.5% of all households were made up of individuals and none had someone living alone who was 65 years of age or older. The average household size was 3.21 and the average family size was 3.23.
On base the population was spread out with 24.0% under the age of 18, 43.5% from 18 to 24, 31.0% from 25 to 44, 1.4% from 45 to 64, and 0.1% who were 65 years of age or older. The median age was 22 years. For every 100 females there were 202.6 males. For every 100 females age 18 and over, there were 258.8 males.
The median income for a household on the base was $34,757, and the median income for a family was $34,918. Males had a median income of $16,436 versus $21,108 for females. The per capita income for the town was $12,983. 7.2% of the population and 6.2% of families were below the poverty line. Out of the total people living in poverty, 9.8% were under the age of 18 and none was 65 or older.