This report on smoking and health, the twenty-third in a series that was begun in 1964, is the first in this series to focus on young people. It underscores the seriousness of tobacco use and its relationship to other adolescent problem behaviors. Examined here are the past few decades' scientific literature on the factors that influence the onset of use among young people and on strategies to prevent this onset. To better understand adolescent tobacco use, this report draws not only on medical and epidemiologic research, but also on behavioral and social investigations. The report is divided into six chapters. Chapter 1 provides a general summary, while chapter 2 concentrates on the health consequences of tobacco use by young people ages 10 through 18. Chapter 3 examines the epidemiologic patterns of tobacco use among the young; chapter 4 considers psychosocial risk factors, and chapter 5 analyzes the influence of tobacco advertising and promotion. The final chapter assesses what has been done--from the individual to the legislative level--to prevent tobacco use among young people. The report's major conclusions include evidence of nearly all first use of tobacco occurring before high school graduation and data on nicotine addiction in adolescents. (Contains a glossary, an index, and approximately 400 references.) (RJM)