Rossmoor is a planned census-designated place located in Orange County, California.

The gated Leisure World retirement community in the city of Seal Beach is to the south of Rossmoor, Los Alamitos is to the east and north, and Long Beach is to the west (on the other side of the San Gabriel River, the 605 freeway and the border with Los Angeles County).

[3] Cortese's original partners in securing the first large parcels of land that would become Rossmoor included California governor Goodwin Knight and Judge Alfred Gittelson, who had also partnered with him in the Lakewood Rancho Estates and the Frematic homes.

(It was Gittelson who later agreed to annex his Rossmoor Shopping Center property to Seal Beach in the late 1960s.)

It is a signature of the Rossmoor community that differentiates it from neighboring cities Los Alamitos and Seal Beach.

[4] Although it is not part of the city of Los Alamitos, it is served under the Los Alamitos "sphere of influence" and was proposed to be annexed to the city by 2007 after the Local Agency Formation Commission reviews the proposal.

[5] Another proposal would combine Rossmoor with adjacent Seal Beach and Los Alamitos to form one city.

At the May 22, 2008 meeting, OC LAFCO recommended that the Rossmoor Incorporation Plan go to a vote of the community.

The proposition for cityhood was resoundingly defeated by a vote of 72% to 28% indicating that the majority of residents desire not be incorporated as a city.

Residents also voted down three separate utility tax proposals by a wide margin.

[10] According to the United States Census Bureau, the CDP has a total area of 1.54 square miles (4.0 km2), all of it land.

According to the 2010 United States Census, Rossmoor had a median household income of $208,807, with 3.3% of the population living below the federal poverty line.

As of the 2020 redistricting, Rossmoor is in the 1st Supervisorial District in Orange County, represented by Republican Andrew Do.

Because Rossmoor is an unincorporated area within Orange County, the Supervisor is the key local elected official.

[33] Federally, Rossmoor is located in California's 45th congressional district, which is represented by Democrat Derek Tran.