As a successful builder, he saw a void in the housing market, and he intended to fill it. An early sales brochure describes Leisure World as the "country club city for happy people 52 years of age and older." Cooperative apartments sold for approximately $9,000 to $11,000 (down payments ranged from $680 to $769). The monthly payments of $92.50 to $103.50 covered all services, as well as principal, taxes, insurance and medical insurance. Prospective buyers were informed that Seal Beach Leisure World would free them from landscape maintenance. Their new apartments had all-electric appliances, as well as extra-wide halls, site-down showers, individually temperature-controlled rooms, electric sockets 24 inches above the baseboards and private patios and gardens. The community would have three clubhouses (a forth was added in 1974 and a fifth in 1997), an amphitheater, large swimming pool, therapeutic system, a nearby shopping center, rolled curbs, extra-wide sidewalks and a security force.

Cortese spent two years researching his pet project before obtaining financing to build. The Federal Housing Administration (today called HUD) backed the cooperative housing venture by guaranteeing 40-year mortgages. Construction began in 1960 on the first parcel of land consisting of 844 units. It sold out in nine weeks, and a selling pace began that continued until completion. Each parcel was developed as a corporation. This pattern was followed in the development of 15 such parcels (note: there was no Mutual 13 and Mutual 17 was organized in 1980). The first residents moved in on June 8, 1962. By November of that year, the development had over 3,000 residents, and by March 1963, there were 4,418 unit sold. Because of the government-guaranteed loans, there were many regulations on how the money was to be used. FHA requirements included annexation to an established city, so Leisure World became annexed to Seal Beach.

The Seal Beach Leisure World community has a unique organized structure. Each resident purchased a share of stock in a Mutual Corporation and another share in the Golden Rain Foundation (GRF). A new buyer paid cash to the seller for the shares of stock which permitted occupancy of the apartment. The new resident makes monthly payments to the GRF, who then prorates a portion of the payment to the Mutuals for service of the mortgage payment carried by the Mutual Corporation, as well as for the maintenance of the property. The GRF is a non-profit corporation established for maintenance and upkeep of the common areas and properties: the main streets, the fold course, the clubhouses, amphitheater, exercise room, library and administration buildings. The newest service is an on-site Post Office building.

The original plan to fund a private on-site medical clinic staffed with doctors, nurses, and various specialists turned out to be cost prohibitive. This plan was replaced by a contract with the Los Alamitos Medical Center to manage the Leisure World Health Care Center (HCC). The HCC provides 24-hour emergency service and regular medical care for residents choosing to use the service. Construction was completed on a new medical building in November 1998.

In the beginning, the community was governed by a Golden Rain Board of Directors appointed by the developer. By 1964, a large group of residents had a growing concern that the builder's interest was in conflict with the residents' interests. They called for reform and held elections that successfully replaced the directors appointed by the builder with elected residents as directors. This resulted in a fundamental change from a builder-dominated organizational structure to a board of directors elected form the people living in the community. This continues to exist today, making Seal Beach Leisure World unique among similar communities.

The GRF Board is made up of elected residents, one from each Mutual (except Mutuals 1 and 2, they elect two members). The GRF Board is responsible for the community-wide facilities and the overall operation of the community. Committees are organized with GRF Board members and are the work group involving issues, projects, fact-finding and policy decisions facing the Board each year (executive, finance, medical, physical property, publications, library, recreation, resales, and security, bus and traffic).

In November 1966, J.L. Moyer became Leisure World's management firm, replacing the Leisure World Foundation, an affiliate of the development company which had been under contract to the Golden Rain Foundation since '64. Since 1998, an administrator and approximately 200 staff members carry out policies as determined by the GRF Board. Staff is employed by the GRF to implement the directives of the Board in running this city within a city.

To further explain the community's unique organization, each Mutual Corporation is like a giant homeowner with a mortgage on a group of residential buildings. As the legal owner, it collects a share of the mortgage payment plus maintenance fees from each of its residents. In return, it services the mortgage and maintains the buildings and grounds. The Mutual establishes reserves for specific purposese, and invests these reserves to earn interest, thereby keeping residents' fees low as possible. Each Mutual Corporation has its own bylaws and its own board of directors elected form its residents.

"Why Golden Rain Foundation?" According to a story published in one of the first issues of the Golden Rain News, the Golden Rain tree is a small tree with bright yellow flowers hanging in drooping clusters. The seeds grow in pods that hang on the tree until the new growth appears. It is described as a gorgeous tree when in bloom because the brilliant blossoms hanging in clusters from the drooping branches can be likened to "golden rain". It was in New Orleans that the developer first saw a Golden Rain tree and fell in love with its beauty. Thus was conceived the idea of making these trees a symbol of the community he was planning for senior citizens. Determining that the tree could live in Southern California, he ordered 2,700 to be sent to a nursery in Chino, where they were carefully nurtured until ready to be planted in Seal Beach Leisure World. Time took its toll on the Golden Rain trees and today only three of the original trees grace the property. Mutual 15 added 20 Golden Rain Trees in 1995.

With approximately 8,600 residents and over 6,000 apartments and condos, the community maintains an impressive schedule of activities. Charter bus trips and over 120 social and service clubs, games, classes and hobby groups provide a wide array of choices to Leisure World residents. The minimum age requirement has been raised from 52 to 55.