To qualitatively project the future health burden of tobacco from present-day young adult smoking behavior. Population surveys in California (2002) and nationally (1978-80, 2001-03). In 2002, 40% of California young adult smokers were nondaily smokers, 24% had quit at some time for >or=6 months, 45% said they smoked less now than previously, and 68% thought they would quit within 5 years. Interest in quitting was high, and most were actively engaged in the smoking cessation process. Young adult smoking behavior changed from 1978-80 to 2001-03. The future health burden from smoking will be less for the current generation of young adults.