The state Department of Finance said Thursday that California added 332,000 people between July 1, 2012 and July 1 of this year. The state population now stands at 38.2 million.
Demographers say the overall 0.9 percent growth rate was the highest since 2003-04, before the recession.
The increase was largely driven by new births. Migration added only 66,000 people.
Alameda and Santa Clara counties in the San Francisco Bay Area saw the largest percentage increases in population, followed by Santa Barbara, Placer and Kern counties. Some remote counties saw population declines.
More than half of all Californians live in just five counties: Los Angeles, San Diego, Orange, Riverside and San Bernardino.