For statistical purposes, the United States Census Bureau has defined Los Alamos as a census-designated place (CDP).

The hills above Rancho Los Alamos served as a hideout for bandito, Salomon Pico, whose escapades were popularized by the character "Zorro".

[5] During the U.S.'s centennial year of 1876, Thomas Bell along with his nephew John S. Bell, and Dr. James B. Shaw (all from San Francisco), purchased acreage from Rancho Los Alamos and neighboring Rancho La Laguna.

[6] Both families allocated a half square mile from each of their new ranches to create the Los Alamos town site with "Centennial Street" as the central thoroughfare.

The Los Alamos Valley prospered and grew quickly serving as a popular stagecoach stop from 1861 to 1901.

The narrow-gauge Pacific Coast Railway also ran to Los Alamos from San Luis Obispo between 1882 and 1940.

Residents today still pick-up their mail from the Post Office downtown, as no street delivery is available.

While Los Alamos is in a narrow valley, the surrounding terrain consists of rolling hills.

Lompoc, California and Vandenberg Air Force Base are to the west and southwest, respectively.

It is a small, unincorporated town in a region of ranches, oil fields, vegetable farms (broccoli, lettuce and strawberries), and wine grape vineyards.

Several of these eateries and wineries were featured in the summer 2012 issue of Edible Santa Barbara.

Los Alamos Old Days is a celebration held in September annually on Bell Street.

In local Spanish, "álamo" refers to Fremont Cottonwood (Populus fremontii) trees, native to the area.

[13] In the 2004 film Sideways, Stephanie, one of the four main characters played by Sandra Oh, lives in Los Alamos.

The town, particularly the Union Hotel, served as the shooting location for the music video for Say Say Say by Michael Jackson and Paul McCartney.