Brentwood is a city in Contra Costa County, California, United States. It is located in the East San Francisco Bay Area. The population was 23,302 at the 2000 census, and has continued to grow.

The downtown is centered around the intersection of Oak Street and First Street, just off Highway 4 (Brentwood Blvd). It is the site of offices, restaurants, a movie theatre and small stores. City Park, City Hall, Brentwood Library and the U. S. Post Office are located along Oak Street.

Over the past several years a great deal of what could be described as "big-box" retail has been introduced in the area of the Brentwood/Antioch border on Lone Tree Way, about 3.5 miles from downtown Brentwood. This includes major tenants such as Kohl's, Trader Joe's, Home Depot, Lowes, Mervyns, Target, Sport Chalet and Barnes & Noble.

Brentwood is known throughout the Bay Area for its agriculture, primarily its cherries, corn and peaches. Brentwood is increasingly residential, with the rate of residential growth in the triple digits during the 1990s and 69% from 2000-2005.