Los Alamitos ("The Little Cottonwoods" in Spanish) is a small city in Orange County, California, United States. The population is around 11,536. It is often mistakenly thought to include the adjacent but unincorporated community of Rossmoor (population just under 11,000) which uses Los Alamitos as its mailing address. Although Rossmoor is not part of Los Alamitos, it is speculated that it may be annexed to the city, or Rossmoor, Seal Beach, and Los Alamitos will combine to form one city.

           The USA Water Polo National Aquatic Center, where the men's and women's US Olympic water polo teams train, is located on the US Military Joint Forces Training Base in Los Alamitos. The facility is also used for major water polo tournaments, swim classes and local swim teams. The Joint Forces Training Base includes the Los Alamitos Army Airfield.

After World War 2, many former military personnel chose to stay on in Los Alamitos. Other than "the base" the area remained unchanged until 1956 when builder Ross Cortese purchased land to build the walled community of Rossmoor just southwest from the townsite of Los Alamitos. Rossmoor, still the largest single development in Orange County, was the first walled community in the United States and quickly became home to over 10,000 upper middle class professionals.           Although Rossmoor never officially became part of Los Alamitos proper, it has become inextricably linked to the town. When Los Alamitos incorporated in 1960 its population was only about 3,400, while still-growing Rossmoor was nearing 10,000. Now they are fairly equal with Los Alamitos being slightly larger than 11,000, and Rossmoor just below that. Rossmoor, still an unincorporated part of Orange County, doesn't pay taxes to Los Alamitos, but the city virtually treats Rossmoor residents as if they were residents. In exchange, the city's many youth programs benefit from the overwhelming number of Rossmoor residents who volunteer for those programs, and homes in Los Alamitos get a significant increase in property values because of their proximity to Rossmoor.
	Schools Los Alamitos High School Laurel High School McAuliffe Middle School (formerly called Pine) Oak Middle School St. Hedwig School, K-8 Private School Hopkinson Elementary Lee Elementary Los Alamitos Elementary Rossmoor Elementary Weaver Elementary
Zoning laws keep out heavy manufacturing or industry, because nearly all the city land is developed. The Armed Forces Reserve Center takes up 48 percent of the city's 4.3 square miles. The rest of the city is a snug fitting mix of homes, apartments, businesses and open space.