California has one of the most diverse societies on earth. Ethnic minorities comprise at least one-third of the state's people, and the society is becoming ever more diverse. It is estimated that by about the year 2010, California will have no majority ethnic group. The historical development of this diversity is traced from the arrival of European settlers, through the Gold Rush migrations and the arrival of Chinese immigrants in the nineteenth century. Successive waves of Japanese American, Mexican American, and other Asian American groups, especially after the reform of immigration law in 1965, enriched the state's heritage. The Los Angeles (California) and San Francisco (California) metropolitan areas are to the late twentieth century what New York was to the late nineteenth, the primary center of new immigration. (SLD)