Regional centers were established through state legislation sponsored primarily by Assemblyman Frank Lanterman. In 1965 pilot projects were initiated in San Francisco and Los Angeles to assist persons with mental retardation and their families in locating or spearheading the development of community services and programs for their special needs.

AB 225 (Lanterman Mental Retardation Services Act) was enacted in 1969 and established a statewide system of regional centers based upon the pilot projects. Seven regional centers were established statewide and since then the number of regional centers has grown to the current number of twenty-one.

In 1974 additional legislation (AB 846 Lanterman) went into effect expanding the clientele served by the regional centers to include persons with cerebral palsy, epilepsy, autism, and other significantly handicapping conditions found to be closely related to mental retardation. It has been estimated that 5% of the population in California has a significant developmental disability. Regional centers currently serve nearly 280,000 people.