Both the City of Los Angeles and Los Angeles County, along with the rest of the nation, are undergoing several revolutionary demographic changes that affect the way we form families, distribute ourselves among various regions, and divide our time between work and other activities. The focus of this paper is on population growth. Had it not been for immigration--mostly from Latin American and Asian countries--the city of Los Angeles would have lost about 250,000 residents between 1970 and 1980; instead it gained 150,000. This sort of thing will not go on indefinitely, however. Indeed, the central fact about Los Angeles's demographic future is that it can no longer expect the rapid growth that it enjoyed in the past. The city and the county are now integrated into a mature metropolis, where population growth will be slow for the rest of the century. Overall, Los Angeles seems certain to face a host of demographic, economic, and social changes that will challenge both the public and private sectors. How Los Angeles responds to those challenges (especially with a population increasingly composed of immigrants and their offspring) remains to be seen.